A negative electrode sheet, a preparation method thereof, a cylindrical battery, and an electronic cigarette

Abstract

A negative electrode sheet provided by the present invention uses pure silicon particles as the negative electrode active material. By controlling the mass ratio of the pure silicon particles in the negative electrode silicon-based active material and coordinating with the adjustment of the areal density and the tap density of the negative electrode sheet, the control of the coating layer thickness of the negative electrode sheet is achieved, thereby improving the energy density and the electrical conductivity of the negative electrode sheet. The present invention also provides a method for preparing a negative electrode sheet. By preferably selecting a conductive agent and a binder and controlling the viscosity and the solid content of the slurry, the preparation of the negative electrode sheet is realized. The present invention further provides a cylindrical battery. By using the above-mentioned negative electrode sheet and changing the width and length of the positive and negative electrode sheets, the preparation of high-energy-density cylindrical batteries of various models can be realized, and at the same time, the battery also has excellent rate performance.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a negative electrode sheet, a preparation method thereof, a cylindrical battery, and an electronic cigarette. Background Art

[0002] Lithium-ion batteries have become an ideal power source for portable electronic devices such as electronic cigarettes due to their advantages of high energy density, long cycle life, and small volume-to-weight ratio. In recent years, with the continuous development of the electronic cigarette market, consumers' expectations for electronic cigarettes have been continuously upgraded. They not only pursue long-lasting battery life but also desire a delicate and rich taste experience. In this context, high-energy-density and high-rate lithium-ion batteries, as the core elements to enhance the overall experience of electronic cigarettes, have a continuously increasing market demand and have become the main driving force for the development of the electronic cigarette industry.

[0003] The high-energy-density state of an electronic cigarette lithium-ion battery is one of the important factors determining its service life. A battery with a high energy density can provide more electrical energy under the same volume and weight, thereby extending the usage time of the electronic cigarette. The high-rate performance of an electronic cigarette lithium-ion battery is an important factor affecting the usage experience of the electronic cigarette. A high-rate electronic cigarette lithium-ion battery can provide a higher discharge current, thus supporting the efficient operation of the electronic cigarette atomizer, generating more smoke and a better taste. However, the energy density and rate performance of lithium-ion batteries are affected by multiple factors, including electrode materials, cell electrode sheet design, manufacturing processes, etc. Therefore, in order to pursue high-energy-density and high-rate electronic cigarette lithium-ion batteries, manufacturers are constantly exploring new battery materials and manufacturing processes to promote the continuous update and iteration of electronic cigarette products.

[0004] For example, Chinese Patent Application Authorization No. CN111342005B discloses a preparation method of an electronic cigarette lithium-ion battery. Its positive electrode uses high-voltage and high-compaction lithium cobaltate, and the lithium cobaltate is coated with an antioxidant on the periphery. The negative electrode uses a silicon-carbon material, combined with an optimized electrolyte formula, so as to realize the preparation of a high-voltage, high-energy-density, and high-rate electronic cigarette lithium-ion battery. However, this method uses a composite material of silicon-carbon and graphite as the negative electrode active material, and the specific capacity of the negative electrode material is only about 500 mAh / g at most, and higher energy density cannot be achieved. Another example is the preparation method of an ultra-large-diameter cylindrical electronic cigarette battery disclosed in Chinese Patent Application Publication No. CN118738292A. Its positive electrode uses lithium cobaltate with high-rate performance and a rate-type ternary composite material, combined with graphite as the negative electrode, and the capacity of the battery is increased by adjusting the positive electrode ratio, surface density, and compaction density; at the same time, a conductive agent with high conductivity is selected to increase the proportion of the active main material, so as to achieve the purpose of improving the volume energy density and rate performance of the battery. However, its negative electrode uses a graphite negative electrode, and the theoretical capacity is only 374 mAh / g, which limits the energy density of the battery.

[0005] Therefore, how to effectively improve the energy density and rate performance of e-cigarette lithium-ion batteries needs to be comprehensively considered from the aspects of electrode materials and electrode sheet design. Silicon materials have been applied in anode materials with a theoretical capacity of 4200 mAh / g. For example, high-capacity materials such as silicon-based, silicon-oxy, and silicon-carbon have been used. However, the addition of a large amount of carbon results in the loss of the high capacity of silicon and cannot meet the requirements of higher energy density. Summary of the Invention

[0006] The purpose of the present invention is to provide a negative electrode sheet, a preparation method thereof, a cylindrical battery, and an e-cigarette. The negative electrode sheet in the present invention uses pure silicon particles as the negative electrode material, which has an extremely high specific capacity and can significantly improve the energy density of the battery. At the same time, by controlling the coating layer thickness of the negative electrode sheet, a thin-type design of the negative electrode sheet is realized, which shortens the migration distance of electrons and ions, is beneficial to reducing the internal resistance of the battery, and improving the rate performance of the battery.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] In the first aspect, the present invention provides a negative electrode sheet, which includes a negative electrode current collector, a negative electrode tab disposed on the negative electrode current collector, and a negative electrode silicon-based active material;

[0009] The negative electrode silicon-based active material includes pure silicon particles, and the mass percentage content of the pure silicon particles in the negative electrode silicon-based active material is 65%-100%;

[0010] The negative electrode silicon-based active material forms a first coating surface and a second coating surface on the upper and lower surfaces of the negative electrode current collector respectively, and the sum of the thicknesses of the first coating surface and the second coating surface is 12 μm - 20 μm;

[0011] In one embodiment, the specific capacity of the pure silicon particles ≥ 3200 mAh / g.

[0012] In one embodiment, the average particle size of the pure silicon particles is 3.0 - 6.0 μm.

[0013] In one embodiment, the double-sided surface density of the negative electrode sheet is 1.6 - 2.4 mg / cm 2 .

[0014] In one embodiment, the tap density of the negative electrode sheet is 1.1 - 1.3 g / cm 3 .

[0015] In one embodiment, the thickness of the negative electrode sheet is 18 μm - 28 μm.

[0016] In one embodiment, the first coating surface and the second coating surface respectively include two negative electrode coating regions, and the negative electrode tab is welded in a first blank area between the two negative electrode coating regions of the first coating surface, or the negative electrode tab is welded in a second blank area between the two negative electrode coating regions of the second coating surface.

[0017] In one embodiment, the distance between the two coating regions is 2-8 times the width of the negative electrode tab.

[0018] In one embodiment, the welding area of the negative electrode tab and the negative electrode plate is greater than 8 mm 2 .

[0019] The beneficial effects of a negative electrode plate provided by the present invention are as follows: By using micron silicon particles with high specific capacity and easy production as the main negative electrode material, not only can the production cost of the main negative electrode material be effectively reduced, but also the requirement of high volume energy density can be achieved. At the same time, by controlling the surface density and compaction density of the negative electrode plate to regulate the thickness of the micron silicon particles on the negative electrode current collector, on the premise of ensuring the lithium storage capacity of the negative electrode plate, the thickness of the coating layer of the negative electrode plate is reduced, the migration distance of lithium ions during charge and discharge is reduced, which is beneficial to improving the migration resistance of lithium ions during charge and discharge, reducing the internal resistance of the negative electrode plate, achieving the purpose of increasing the current, and improving the electrical conductivity of the negative electrode plate.

[0020] In the second aspect, the present invention also provides a preparation method of the above-mentioned negative electrode plate, including the following steps:

[0021] A: Dispersing pure silicon particle material, conductive agent and binder evenly in a solvent to obtain a negative electrode coating slurry, the solid content of the negative electrode slurry is 10-15 wt%, and the viscosity of the negative electrode slurry is 4000-15000 mPa·s -1 ;

[0022] B: Coating the negative electrode coating slurry on the surface of the current collector, and obtaining the negative electrode plate after drying and rolling.

[0023] The beneficial effects of a preparation method of a negative electrode plate provided by the present invention are as follows: By using conductive agents with relatively high specific surface areas to increase the total specific surface area of all microparticles in the slurry, and matching with a binder system with better thickening effect, and preferably a better mixing order, the fluidity and stability of the slurry are ensured, so that the uniformity and consistency of coating can be ensured even when the negative electrode is coated thinly, and the phenomena of scratches and uneven thickness can be avoided.

[0024] In the third aspect, the present invention also provides a cylindrical battery, including an aluminum-plastic shell, an electrolyte placed inside the shell, and a cylindrical winding core, and the cylindrical winding core includes a positive electrode plate, a separator and the above-mentioned negative electrode plate.

[0025] In one embodiment, the positive electrode plate includes a positive electrode current collector, a positive electrode tab disposed on the positive electrode current collector, and a positive electrode active material, and the positive electrode active material is one of lithium manganate or lithium cobaltate.

[0026] In one embodiment, the positive electrode active material is lithium cobaltate, and the proportion of lithium cobaltate in the positive electrode active material is 80-100 wt%.

[0027] In one embodiment, the average particle size of the lithium cobaltate is 4.5-6.0 μm.

[0028] In one embodiment, the positive electrode active material forms a third coating surface and a fourth coating surface on the upper and lower surfaces of the positive electrode current collector respectively; the third coating surface and the fourth coating surface each include two positive electrode coating regions, and the positive electrode tab is welded in the third blank area between the two positive electrode coating regions of the third coating surface, or the positive electrode tab is welded in the fourth blank area between the two positive electrode coating regions of the fourth coating surface.

[0029] In one embodiment, the length of the positive electrode plate is 745-750 mm, and the width is 20-25 mm; the length of the negative electrode plate is 800-805 mm, and the width is 20-25 mm; at a discharge rate of 0.2C, the battery capacity of the cylindrical battery is 580-700 mAh.

[0030] In one embodiment, the length of the positive electrode plate is 745-750 mm, and the width is 25-30 mm; the length of the negative electrode plate is 800-805 mm, and the width is 25-30 mm; at a discharge rate of 0.2C, the battery capacity of the cylindrical battery is 710-810 mAh.

[0031] In one embodiment, the length of the positive electrode plate is 745-750 mm, and the width is 30-35 mm; the length of the negative electrode plate is 800-805 mm, and the width is 30-35 mm; at a discharge rate of 0.2C, the battery capacity of the cylindrical battery is 820-920 mAh.

[0032] In one embodiment, the length of the positive electrode plate is 1300-1320 mm, and the width is 25-35 mm; the length of the negative electrode plate is 1360-1380 mm, and the width is 25-35 mm; at a discharge rate of 0.2C, the battery capacity of the cylindrical battery is 1000-1600 mAh.

[0033] In one embodiment, the length of the positive electrode plate is 1300 - 1320 mm, and the width is 40 - 45 mm; the length of the negative electrode plate is 1360 - 1380 mm, and the width is 40 - 45 mm; at a discharge rate of 0.2C, the battery capacity of the cylindrical battery is 2100 - 2400 mAh.

[0034] In one embodiment, the length of the positive electrode plate is 1300 - 1320 mm, and the width is 50 - 55 mm; the length of the negative electrode plate is 1360 - 1380 mm, and the width is 50 - 55 mm; at a discharge rate of 0.2C, the battery capacity of the cylindrical battery is 2500 - 2900 mAh.

[0035] The beneficial effects of a cylindrical battery provided by the present invention are as follows: By using the above-mentioned negative electrode plate with pure silicon particles as the negative electrode material, the high-capacity characteristics of the silicon material are fully utilized, significantly improving the battery capacity. Through optimizing the manufacturing process of the electrode plate, the high-rate discharge characteristics of the battery are achieved simultaneously, enhancing the comprehensive performance of the cylindrical battery, meeting the urgent market demand for high-performance, high-capacity, safe and reliable battery products, and having broad market application prospects and social value; Using the above-mentioned negative electrode plate can meet the design requirements of cylindrical batteries of different sizes, and can be customized according to the needs of different electronic devices, and is widely used in multiple fields such as portable electronic devices, electric vehicles, and energy storage systems, demonstrating broad applicability and market competitiveness.

[0036] Fourthly, the present invention also provides an electronic cigarette, including the above-mentioned cylindrical battery.

[0037] The beneficial effects of an electronic cigarette provided by the present invention are as follows: By using the above-mentioned cylindrical battery, it can provide a longer battery life for the electronic cigarette, meet the user's requirements for high performance and long standby time, and improve the user experience. Description of the Drawings

[0038] Figure 1 It is a schematic structural diagram of the first coating surface of the negative electrode current collector of a negative electrode plate provided by the present invention;

[0039] Figure 2 It is a schematic structural diagram of the second coating surface of the negative electrode current collector of a negative electrode plate provided by the present invention;

[0040] Figure 3 It is a side view of the negative electrode current collector of a negative electrode plate provided by the present invention;

[0041] Figure 4 It is a schematic structural diagram of the third coating surface of the positive electrode current collector of a positive electrode plate provided by the present invention;

[0042] Figure 5 Schematic diagram of the structure of the fourth coating surface of the positive current collector of a positive electrode plate provided by the present invention;

[0043] Figure 6 Side view of the positive current collector of a positive electrode plate provided by the present invention;

[0044] Figure 7 Schematic diagram of the structure of a cylindrical battery provided by the present invention;

[0045] Description of reference numerals:

[0046] 100, cylindrical battery; 10, negative electrode plate; 20, positive electrode plate; 30, separator; 40, aluminum-plastic shell;

[0047] 11, negative current collector;

[0048] 111, first coating surface; 111A, first coating area; 111B, second coating area; 111C, first blank area;

[0049] 112, second coating surface; 112A, third coating area; 112B, fourth coating area; 112C, second blank area;

[0050] 113, first side; 114, second side;

[0051] 12, negative electrode tab; 121, first conductive sheet; 121A, first ultrasonic welding mark; 122, first insulating sheet; 123, second insulating sheet;

[0052] 21, positive current collector;

[0053] 211, third coating surface; 211A, fifth coating area; 211B, sixth coating area; 211C, third blank area;

[0054] 212, fourth coating surface; 212A, seventh coating area; 212B, eighth coating area; 212C, fourth blank area;

[0055] 213, third side; 214, fourth side;

[0056] 22, positive electrode tab; 221, second conductive sheet; 221A, second ultrasonic welding mark; 222, third insulating sheet; 223, fourth insulating sheet. Detailed implementation manners

[0057] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0058] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0059] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way is inclusive and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range.

[0060] If not otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution.

[0061] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0062] If not specifically stated, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.

[0063] As the demand for lithium-ion battery energy density becomes higher and higher, and the charging time requirement becomes shorter and shorter, the theoretical capacity of 374mAh / g of graphite negative electrode gradually limits the development of batteries in the field of high energy density. Silicon negative electrode with high theoretical capacity is regarded as the most promising negative electrode material for high specific energy lithium-ion battery. Compared with nano silicon, micron silicon has lower raw material cost, higher tap density and smaller surface area, and has advantages in improving volume energy density and limiting interface side reactions. Therefore, the inventors of this application selected micron pure silicon with high gram capacity as the negative electrode active material, and controlled the surface density and compaction density of the negative electrode plate 10 to achieve the regulation of the thickness of the negative electrode plate 10, so as to reduce the thickness of the negative electrode plate 10 as much as possible, reduce the migration distance of lithium ions during charging and discharging, improve the migration resistance of lithium ions during charging and discharging, and improve the conductivity of the negative electrode plate 10, so as to achieve the improvement of energy density and rate performance of lithium-ion batteries.

[0064] like Figures 1-3As shown in the figure, it is a schematic structural diagram of a negative electrode plate 10 provided by the present invention. In the present invention, the length direction of the negative electrode plate 10 itself is defined as X, the width direction is defined as Y, and the thickness direction is defined as Z. It should be understood that the above definitions of directions are for the purpose of conveniently describing the present invention, and the directions defined by the present invention can be understood according to the relative positions of the drawings and the actual products. It can be understood that the length direction, width direction, and thickness direction of the negative electrode current collector 11 and the negative silicon-based active material itself are the same as those of the negative electrode plate 10. Figure 1 and Figure 2 As shown in the figure, the negative electrode plate 10 in an embodiment of the present invention is along its own length direction X, Figure 3 As shown in the figure, the negative electrode plate 10 in an embodiment of the present invention is along its own thickness direction Z.

[0065] As Figures 1-3 shown in the figure, the negative electrode plate 10 provided by the present invention includes a negative electrode current collector 11, a negative electrode tab 12 provided on the negative electrode current collector 11, and a negative silicon-based active material. The negative electrode current collector 11 includes a first coating surface 111 and a second coating surface 112 provided along its own thickness direction Z. The negative silicon-based active material provided by the present invention is provided on both the first coating surface 111 and the second coating surface 112 of the negative electrode current collector 11.

[0066] Among them, as Figure 1 and Figure 3 shown in the figure, the negative silicon-based active material forms a first coating surface 111 on the upper surface of the negative electrode current collector 11. A first coating area 111A and a second coating area 111B are provided on the first coating surface 111, and the lengths of the first coating area 111A and the second coating area 111B are the same. The thickness of the first coating area 111A is the thickness of the active material formed after the negative silicon-based active material is coated and rolled on the upper surface of the negative electrode current collector 11. A first blank area 111C is also provided between the first coating area 111A and the second coating area 111B. There is no negative silicon-based active material in the first blank area 111C, and the first blank area 111C is used for welding the negative electrode tab 12. A first side 113 is also provided on the first coating surface 111. There is no negative silicon-based active material in the first side 113. The first blank area 111C and the first side 113 without the negative silicon-based active material are the surfaces of the negative electrode current collector 11 itself.

[0067] As Figures 2-3As shown, the negative electrode silicon-based active material forms a second coating surface 112 on the lower surface of the negative electrode current collector 11. A third coating area 112A and a fourth coating area 112B are provided on the second coating surface 112, and the third coating area 112A and the fourth coating area 112B have the same length. The thickness of the second coating surface 112 is the thickness of the active material formed after the negative electrode silicon-based active material is coated and rolled on the lower surface of the negative electrode current collector 11. A second blank area 112C is also provided between the third coating area 112A and the fourth coating area 112B. There is no negative electrode silicon-based active material in the second blank area 112C, and the second blank area 112C is the back surface of the first blank area 111C where the negative electrode tab 12 is welded. A second side edge 114 is also provided on the second coating surface 112. There is no negative electrode silicon-based active material in the second side edge 114. The second blank area 112C and the second side edge 114 without the negative electrode silicon-based active material are the surfaces of the negative electrode current collector 11 itself.

[0068] In order to better control the stability of the negative electrode silicon-based active material on the negative electrode current collector 11 during the operation of the battery and improve the conductivity of the negative electrode silicon-based active material, the thickness of the first coating surface 111 of the negative electrode plate 10 in the present invention is 6 μm - 10 μm; the thickness of the second coating surface 112 is 6 μm - 10 μm. The sum of the thicknesses of the first coating surface 111 and the second coating surface 112 on the negative electrode plate 10 is controlled between 12 μm - 20 μm, so that the thickness of the negative electrode plate 10 is much smaller than that of the traditional negative electrode plate. The thicknesses of the negative electrode silicon-based active materials provided on the first coating surface 111 and the second coating surface 112 of the negative electrode plate 10 provided by the present invention can be the same or different, that is, the thickness of the first coating surface 111 and the thickness of the second coating surface 112 can be the same, or the thickness of the first coating surface 111 is larger than the thickness of the second coating surface 112, or the thickness of the first coating surface 111 is smaller than the thickness of the second coating surface 112. The thickness of the negative electrode silicon-based active material on the first coating surface 111 or the thickness of the negative electrode silicon-based active material on the second coating surface 112 can be adjusted separately as needed. When adjusting the thicknesses of the negative electrode silicon-based active materials on the two surfaces separately, the sum of the thicknesses of the two coating surfaces needs to be controlled between 12 μm - 20 μm. By controlling the sum of the thicknesses of the first coating surface 111 and the second coating surface 112 of the negative electrode plate 10 between 12 μm - 20 μm, the present invention can effectively shorten the transmission distance of electrons and lithium ions inside the electrode plate, which helps to reduce the internal resistance of the battery and improve the rate performance of the battery.

[0069] The negative silicon-based active material used in the negative electrode sheet 10 provided by the present invention includes pure silicon particles. The mass percentage content of pure silicon in the negative silicon-based active material is 65-100%. For example, the mass percentage content of pure silicon in the negative silicon-based active material is 65%, 75%, 85%, 95%, 100%, or any value between any two of the above numerical ranges. It should be noted, however, that 100% pure silicon is only discussed as a theoretical limit value. In practical applications, since it is difficult for pure silicon in its natural state to reach a completely impurity-free state, the so-called "100% pure silicon" actually does not exist. Even after a highly refined process, trace impurity elements such as iron, aluminum, and calcium will still be contained in the silicon material. The negative silicon-based active material provided by the present invention can be pure silicon, or a combination of pure silicon and graphite, or pure silicon and silicon-carbon material, or silicon composite material.

[0070] When the negative silicon-based active material is pure silicon and graphite, or pure silicon and silicon-carbon material, or silicon composite material, the mass percentage content of pure silicon in the negative silicon-based active material is controlled at 65-100%. By selecting a negative electrode active material containing pure silicon particles, the present invention enables the battery to have a significantly higher energy density, allowing it to store more electrical energy at the same weight or volume. In addition, compared to other high-performance negative electrode materials, pure silicon particles have a relatively low cost, which gives them a potential cost advantage in large-scale commercial applications.

[0071] In one embodiment, the gram capacity of the pure silicon particles in the negative electrode active material provided by the present invention is ≥3200 mAh / g. As the main body for lithium storage in the battery, the negative silicon-based active material realizes the insertion and extraction of lithium ions during charge and discharge. The selection of different negative silicon-based active materials will directly affect the lithium storage capacity of the entire lithium-ion battery, that is, the capacity of a single battery. By selecting pure silicon particles with a high gram capacity as the key component of the negative electrode active material, the present invention ensures the energy density of the negative silicon-based active material.

[0072] In one embodiment, the average particle size of the pure silicon particles in the negative electrode active material provided by the present invention is 3.0 - 6.0 μm. Such as 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, preferably any value between any two of the above numerical ranges. By optimizing the particle size of the pure silicon particles, the particle size of the pure silicon particles is in the range of 3.0 - 6.0 μm, which helps to shorten the diffusion path of lithium ions inside the pure silicon particles, thereby improving the charge and discharge rate of the battery. In addition, the pure silicon particles with a smaller particle size can provide more inter-particle contact points, which helps to disperse the stress caused by volume change and improve the stability of the battery.

[0073] In one embodiment, the double-sided areal density of the negative electrode sheet 10 is 1.6 - 2.4 mg / cm 2 . For example, the areal density of the two coated surfaces of the negative electrode sheet 10 is 1.6 mg / cm 2 , 1.8 mg / cm 2 , 2.0 mg / cm 2 , 2.2 mg / cm 2 , 2.4 mg / cm 2 or any value between any two of the above numerical ranges. In the present invention, the areal density value is rounded to one decimal place when designed and recorded, but in actual production, slight fluctuations in the areal density value still need to be considered and ensured to be within a controllable range. By optimizing the double-sided areal density of the negative electrode sheet 10, the present application can achieve the regulation of the thickness of the negative electrode sheet 10, improve the utilization rate of the negative electrode material, and thus increase the capacity and energy density of the battery.

[0074] In the present invention, the double-sided areal density of the negative electrode sheet 10 refers to the mass of the negative electrode active material per unit area, and the negative electrode active material is coated on both the upper and lower surfaces of the negative electrode sheet 10. The measurement method of the unit areal density of the negative electrode sheet 10: Step 1. Use a sampler to take a circular foil of a preset area on the empty foil material for weighing to obtain the foil weight; Step 2. Use a sampler to take a circular electrode sheet of the same size on the double-sided coated electrode sheet for weighing, subtract the foil weight in Step 1, and divide by the circular area to obtain the unit areal density; Steps 1 - 2 can be repeated, and the average value can be obtained after obtaining the actual areal density at different positions of the negative electrode sheet 10.

[0075] When the double-sided areal density of the negative electrode sheet 10 is greater than 2.4 mg / cm 2When it does, it means that more negative electrode active material is loaded on the same area, which may theoretically increase the battery capacity. However, an excessively high areal density will increase the thickness of the negative electrode sheet 10, resulting in an increase in the internal resistance of the battery and affecting the charge and discharge efficiency of the battery, thus limiting the improvement of the battery capacity to a certain extent. When the double-sided areal density of the negative electrode sheet 10 is less than 1.6 mg / cm 2 When it is, that is, the active material coated on both sides is reduced. Having less active material in the coating means that the number of lithium ions that can be stored and released during the charge and discharge process decreases, and the energy that can be stored per unit volume also decreases. Therefore, the battery capacity will also decrease.

[0076] In one embodiment, the tap density of the negative electrode sheet 10 is 1.10 - 1.30 g / cm 3 . For example, the tap density of the negative electrode sheet 10 is 1.10 g / cm 3 , 1.15 g / cm 3 , 1.20 g / cm 3 , 1.25 g / cm 3 , 1.30 g / cm 3 or any value between any two of the above numerical ranges. In the present invention, when the tap density value is designed and recorded, the areal density value is rounded to two decimal places by the rounding-off method. However, in actual production, slight fluctuations in the areal density value still need to be considered, and it is ensured that such fluctuations are within a controllable range. By controlling the tap density of the negative electrode sheet 10, the porosity and void distribution of the negative electrode sheet 10 can be controlled, so that the ion conduction ability of the battery during the charge and discharge process can be adjusted, and then the rate performance of the battery can be changed. When the tap density of the negative electrode sheet 10 is greater than 1.30 g / cm 3 , an excessively high tap density easily causes excessive stress inside the negative electrode sheet 10, resulting in fragmentation of the internal particles of the negative electrode silicon-based material and affecting the performance of the electrode sheet; when the tap density of the negative electrode sheet 10 is less than 1.10 g / cm 3 , too low a tap density will, on the one hand, lead to insufficient filling of the active substance in the negative electrode sheet 10, thereby reducing the battery capacity, and on the other hand, it may also lead to an increase in the voids inside the negative electrode sheet 10, thus increasing the internal resistance of the battery and affecting the rate performance of the battery.

[0077] The inventors of the present application utilized the principle of the interaction between the compaction density and the unit surface density of the negative electrode plate 10. By regulating the compaction density and the double-sided surface density of the negative electrode plate 10, the thickness of the negative electrode silicon-based active material on the negative electrode current collector 11 was controlled. By preferably selecting the negative electrode copper foil current collector, the thickness of the current collector was controlled within the range of 6 - 8 μm, so that the thickness of the entire negative electrode plate 10 was controlled between 18 μm and 28 μm. Such precise control of the thickness of the negative electrode plate 10 helps to reduce the voids inside the battery, thereby reducing the internal resistance of the battery and improving the charge and discharge efficiency and power output capacity of the battery. At the same time, the volume specific capacity of the battery can be optimized, and thus the energy density of the battery can be increased.

[0078] In one of the embodiments, the first coating surface 111 and the second coating surface 112 of the negative electrode plate 10 each include two negative electrode coating regions. Among them, the negative electrode tab 12 is disposed in the first blank area 111C between the two negative electrode coating regions of the first coating surface 111. The negative electrode tab 12 can also be disposed in the second blank area 112C between the two negative electrode coating regions of the second coating surface 112. The lengths of the first coating region 111A and the second coating region 111B included in the first coating surface 111 of the negative electrode plate 10 are the same, and the lengths of the third coating region 112A and the fourth coating region 112B included in the second coating surface 112 of the negative electrode plate 10 are also the same.

[0079] The negative electrode plate 10 provided by the present invention, as Figures 1-3 shown, the negative electrode tab 12 is disposed at the middle position of the first blank area 111C between the two negative electrode coating regions of the first coating surface 111. Such a setting enables electrons to flow from the first coating region 111A and the second coating region 111B on both sides of the first blank area 111C to the negative electrode tab 12 simultaneously; or to flow from the negative electrode tab 12 to the first coating region 111A and the second coating region 111B on both sides of the first blank area 111C, which can shorten the path of electrons in the negative electrode plate 10, thereby reducing the internal resistance of the negative electrode plate 10 and improving the rate performance of the battery.

[0080] In one embodiment of the present invention, the negative electrode tab 12 includes a first conductive sheet 121 and a first insulating sheet 122. The first conductive sheet 121 is welded to the first blank area 111C of the first coating surface 111 by a first ultrasonic weld 121A. The first insulating sheet 122 is attached to the first conductive sheet 121 and the negative electrode current collector 11 to protect the first conductive sheet 121 in the first insulating sheet 122 to prevent the positive and negative electrodes from being short-circuited due to the burrs generated by the first conductive sheet 121. Similarly, the second blank area 112C of the second coating surface 112, that is, the side away from the negative electrode tab 12, is also attached with a second insulating sheet 123 to prevent the positive and negative electrodes from being short-circuited due to the burrs generated by the first conductive sheet 121. In this embodiment, the first conductive sheet 121 in the negative electrode tab 10 is a copper-nickel tab with a width of 2-4 mm, and the first insulating sheet 122 and the second insulating sheet 123 are made of polyimide tape.

[0081] In one embodiment, the distance between the two coating areas of the first coating surface 111 of the negative electrode plate 10 is 2-8 times the width of the negative electrode tab 12. In the present invention, the width of the negative electrode tab 12 is preferably 2-4 mm, and the distance between the first coating area 111A and the second coating area 111B is preferably 4-32 mm. By reasonably setting the distance between the two coating areas, it can be ensured that the space between the negative electrode tab 12 and the two coating areas is fully utilized, which helps to increase the filling amount of active materials within a limited battery volume, thereby increasing the energy density of the battery. When the distance between the first coating area 111A and the second coating area 111B is too narrow, it may cause current concentration, increase local resistance and heat generation, and increase the risk of thermal runaway. When the distance between the first coating area 111A and the second coating area 111B is too wide, it means that the area on the negative electrode plate 10 where the active material is not coated is larger, which will result in a reduction in the filling amount of the negative electrode active material, thereby reducing the energy density of the battery.

[0082] In one embodiment, the welding area between the negative electrode tab 12 and the negative electrode plate 10 is greater than 8 mm 2 . Ensure that the welding area is larger than 8mm 2 The purpose is: on the one hand, to ensure that the connection between the negative electrode tab 12 and the negative electrode sheet 10 is more stable and reliable, which helps to reduce the risk of local overheating and thermal runaway caused by poor connection; on the other hand, the increase in the welding area will reduce the contact resistance between the negative electrode tab 12 and the negative electrode sheet 10, which helps to improve the charge and discharge efficiency and rate performance of the battery.

[0083] In a second aspect, the present invention further provides a method for preparing a negative electrode sheet 10, comprising the following steps:

[0084] A: The pure silicon particle material, conductive agent, and binder are uniformly dispersed in a solvent to obtain a negative electrode coating slurry. The solid content of the negative electrode slurry is 10-15 wt%, and the viscosity of the negative electrode slurry is 4000-15000 mPa·s -1 ;

[0085] B: The negative electrode coating slurry is coated on the surface of the current collector, and after drying and rolling, the negative electrode plate 10 is obtained.

[0086] In the present invention, the conductive agent includes one-dimensional conductive agents, two-dimensional conductive agents, and super carbon black (SP). The one-dimensional conductive agent preferably includes one or several of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), carbon nanofibers (CNFs), silver nanofibers, and copper nanofibers; the two-dimensional conductive agent includes graphene (RGO) and / or graphdiyne (GDY). Since super carbon black and one-dimensional conductive agents have a large specific surface area, adding them can increase the surface energy and improve the viscosity of the slurry, but it is not conducive to the dispersion of the slurry. Therefore, it is also necessary to add two-dimensional conductive agents, such as graphene. The addition of graphene can play a lubricating role and make the slurry easier to disperse. The present invention preferably uses single-walled carbon nanotubes, super carbon black, and graphene as the negative electrode conductive agent, and the conductive agent can be in the form of a slurry. The mass ratio of the pure silicon particles to the conductive agent is preferably (80-99):(0.5-20), more preferably (85-95):(5-15).

[0087] In the present invention, the binder includes one or more of polyacrylic acid (PAA), polyacrylamide (PAM), sodium alginate (SA), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR); the addition of polyacrylic acid (PAA), polyacrylamide (PAM), sodium alginate (SA), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) can all improve the viscosity of the slurry. The present invention preferably uses polyacrylic acid (PAA) and polyacrylamide (PAM) as the negative electrode binder, and the binder can be in the form of a slurry. The mass ratio of the pure silicon particles to the conductive agent is preferably (80-99):(0.5-20), more preferably (80-95):(5-15).

[0088] In the present invention, taking the total mass of pure silicon particles, conductive agent, and binder as 100%, the proportion of pure silicon particles is 80 - 99%, preferably 85 - 95%, such as 85%, 90%, 95%, and preferably a range value with any of the above-mentioned values as the upper or lower limit. The proportion of the conductive agent is 0.5 - 20%, more preferably 0.5 - 10%, such as 0.5%, 5%, 10%, and preferably a range value with any of the above-mentioned values as the upper or lower limit. The proportion of the binder is 0 - 20%, more preferably 0.5 - 10%, such as 0.5%, 5%, 10%, and preferably a range value with any of the above-mentioned values as the upper or lower limit. In the present invention, the solvent is preferably deionized water.

[0089] In the present invention, the solid content of the negative electrode slurry is controlled at 10 - 15 wt%, and the viscosity is controlled at 4000 - 15000 mPa·s -1 . The solid content directly affects the uniformity during coating. If the solid content is too high, the fluidity of the slurry may be poor, making it difficult to form a uniform coating on the electrode sheet, thus affecting the performance of the battery; if the solid content is too low, on the one hand, it will bring difficulties in coating, and on the other hand, it may cause the active materials inside the electrode to be easily peeled off or lost during the charge-discharge cycle, damaging the stability of the electrode structure, and thus shortening the service life of the battery. In the present invention, when the solid content is within the range of 10 - 15 wt% and the viscosity is within the range of 4000 - 15000 mPa·s -1 , the fluidity of the slurry is moderate. The slurry is both easy to level and convenient for drying, which is beneficial to improving the coating efficiency and ensuring the performance of the battery.

[0090] In the present invention, the pure silicon particles, binder, and conductive agent are mixed and stirred evenly in deionized water according to the mass ratio of (80 - 95):(5 - 15):(5 - 15) to prepare the negative electrode slurry. To ensure the uniformity of dispersion, the mixing time is preferably more than 3 hours. Preferably, the one-dimensional conductive agent is added last. This is because one-dimensional conductive agents, such as carbon nanotubes (CNT), etc., have a unique fibrous structure and are prone to agglomeration under the action of van der Waals forces. To avoid the occurrence of agglomeration phenomena, it is usually necessary to add them at the final stage of the mixing process. This can ensure that the conductive agent can be quickly and evenly dispersed in the electrode material after addition, thereby improving its conductivity.

[0091] In the present invention, the current collector can be copper foil, carbon-coated copper foil, or three-dimensional porous copper foil, and the thickness of the current collector is controlled at 6 μm - 8 μm, preferably 6 μm or 8 μm.

[0092] The present invention has no special limitation on the coating method, and the commonly used coating methods by those skilled in the art can be adopted.

[0093] In the present invention, the drying temperature is preferably 70 - 120 °C, more preferably 80 - 100 °C, such as 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, and is preferably a range value with any of the above-mentioned values as the upper or lower limit.

[0094] In the present invention, by using various conductive agents with relatively high specific surface areas, the total specific surface area of all the microparticles in the slurry is increased. In combination with a binder system with better thickening effect, and preferably a better mixing sequence, the fluidity of the slurry is ensured, enabling it to be mixed evenly in a relatively short time.

[0095] In a third aspect, the present invention also provides a cylindrical battery 100, such as Figure 7 shown, which is a schematic structural diagram of the cylindrical battery 100 provided by the present invention. The cylindrical battery 100 provided by the present invention includes an aluminum-plastic shell 40, a positive electrode plate 20, a negative electrode plate 10, a cylindrical winding core formed by a separator 30, and an electrolyte disposed inside the shell. Inside the aluminum-plastic shell 40, the separator 30, the negative electrode plate 10, the separator 30, and the positive electrode plate 20 are wound in sequence to form a cylindrical winding core. An electrolyte is disposed inside the aluminum-plastic shell 40. One end outside the shell is the positive electrode end, and the other end is the negative electrode end.

[0096] In one embodiment, the cylindrical battery 100 provided by the present invention further includes a positive electrode plate 20. As Figures 4-6 shown, which is a schematic structural diagram of the positive electrode plate 20 provided in the cylindrical battery 100 provided by the present invention. The positive electrode plate 20 includes a positive electrode current collector 21, a positive electrode tab 22 disposed on the positive electrode current collector 21, and a positive electrode active material. The positive electrode active material can be selected from one of lithium manganate or lithium cobaltate, and both can be combined with the negative electrode plate 10 in the present invention to obtain a high-performance cylindrical battery 100. Due to certain requirements of the e-cigarette industry for high voltage and high rate of the battery, lithium iron phosphate and ternary materials are limited in their applications to a certain extent because of their relatively low voltages.

[0097] The cathode active material in the cathode electrode sheet 20 provided by the present invention is lithium cobaltate, and the proportion of lithium cobaltate in the cathode active material is 80-100 wt%. Lithium cobaltate has a relatively high first discharge specific capacity. When the proportion of lithium cobaltate in the cathode active material of the present invention reaches 80-100 wt%, it indicates that lithium cobaltate is the main component of the cathode material. This is because it is difficult to obtain 100% pure lithium cobaltate in actual production and application. The present invention uses high-content lithium cobaltate as the cathode active material of the e-cigarette battery, which can store more electrical energy and provide a longer battery life. In addition, the voltage platform of lithium cobaltate is usually higher than that of many other common lithium-ion battery cathode materials, and the charging voltage of high-voltage lithium cobaltate materials can even reach as high as 4.3V or even 4.4V. Selecting lithium cobaltate as the cathode active material to prepare the e-cigarette lithium battery helps to provide a more stable voltage output during the operation of the e-cigarette and ensure the normal operation of the e-cigarette.

[0098] In one embodiment, the average particle size of the lithium cobaltate, which is the cathode active material provided by the present invention, is 4.5-6.0 μm. Such as 4.5 μm, 5.0 μm, 5.5 μm, 6.0 μm, preferably any value within any two of the above numerical ranges. By using small particle size lithium cobaltate particles in the present invention, it is beneficial to the insertion and extraction of Li + , shortens the transmission path of ions and electrons inside the material, reduces the internal resistance, and further improves the performance of the battery.

[0099] In the cathode electrode sheet 20 provided by the present invention, such as Figure 6The positive current collector 21 shown includes a third coating surface 211 and a fourth coating surface 212 disposed along its own thickness direction Z. The third coating surface 211 includes a fifth coating area 211A and a sixth coating area 211B, and the fourth coating surface 212 includes a seventh coating area 212A and an eighth coating area 212B. The positive active material is disposed on the fifth coating area 211A and the sixth coating area 211B of the third coating surface 211, and on the seventh coating area 212A and the eighth coating area 212B of the fourth coating surface 212, that is, the positive active material is located on two opposite surfaces of the positive current collector 21 respectively. The lengths of the fifth coating area 211A and the sixth coating area 211B included in the third coating surface 211 of the positive electrode tab 20 are the same. The lengths of the coating areas, the seventh coating area 212A and the eighth coating area 212B, included in the fourth coating surface 212 of the positive electrode tab 20 are also the same. A third side edge 213 is simultaneously provided on the third coating surface 211. There is no negative silicon-based active material within the third side edge 213, and the third blank area 211C without the positive active material and the third side edge 213 are the surfaces of the positive current collector 21 itself. A fourth side edge 214 is simultaneously provided on the fourth coating surface 212. There is no negative silicon-based active material within the fourth side edge 214, and the positive electrode tab 22 is disposed within the third blank area 211C between the two positive coating areas of the third coating surface 211, or within the fourth blank area 212C between the two positive coating areas of the fourth coating surface 212.

[0100] The positive electrode tab 20 provided by the present invention, as Figures 4-6 shown, the positive electrode tab 22 is disposed at the middle position of the third blank area 211C between the two positive coating areas of the third coating surface 211. With such a setting, electrons can flow from the fifth coating area 211A and the sixth coating area 211B on both sides of the third blank area 211C to the positive electrode tab 22 simultaneously; or flow from the positive electrode tab 22 to the fifth coating area 211A and the sixth coating area 211B on both sides of the third blank area 211C, which can shorten the path of electrons in the positive electrode tab 20, thereby reducing the internal resistance of the positive electrode tab 20, which helps to improve the charge and discharge efficiency of the battery and improve the rate performance of the battery.

[0101] In one embodiment of the present invention, the positive electrode tab 22 includes a second conductive sheet 221 and a third insulating sheet 222. The second conductive sheet 221 is welded to the third blank area 211C of the third coating surface 211 by a second ultrasonic weld 221A. The third insulating sheet 222 is attached to the second conductive sheet 221 and the positive electrode current collector 21 to protect the second conductive sheet 221 in the third insulating sheet 222 to prevent the positive and negative electrodes from being short-circuited due to the burrs generated by the second conductive sheet 221. Similarly, a fourth insulating sheet 223 is also attached to the fourth blank area 212C of the fourth coating surface 212, that is, the side away from the positive electrode tab 22, to prevent the positive and negative electrodes from being short-circuited due to the burrs generated by the second conductive sheet 221.

[0102] The width of the positive electrode tab 22 of the positive electrode sheet 20 provided by the present invention is the same as the width of the negative electrode tab 12 of the negative electrode sheet 10. That is, the width of the second conductive sheet 221 in the positive electrode sheet 20 is the same as the width of the first conductive sheet 121 in the negative electrode sheet 10. In this embodiment, the second conductive sheet 221 in the positive electrode sheet 20 is an aluminum tab with a width of 2-4 mm, and the third insulating sheet 222 and the fourth insulating sheet 223 are made of polyimide tape.

[0103] In one embodiment of the present invention, the length of the negative electrode sheet 10 is greater than the length of the positive electrode sheet 20, and the negative electrode sheet 10 covers the positive electrode sheet 20. Specifically, the length of the third side 213 or the fourth side 214 of the positive electrode sheet 20 is greater than the first side 113 or the second side 114 of the negative electrode sheet 10, and the length of the third blank area 211C or the fourth blank area 212C of the positive electrode sheet 20 is greater than the length of the first blank area 111C or the second blank area 112C of the negative electrode sheet 10, so that the negative electrode active material can completely cover the positive electrode active material to avoid lithium deposition of the negative electrode sheet 10 and / or the positive electrode sheet 20. In the cylindrical winding process of the present invention, the separator 30 is rolled in first, and the positive electrode sheet 20 is rolled in after the negative electrode sheet 10 is rolled in 1.5 turns, so that the negative electrode sheet 10 covers the positive electrode sheet 20, and the outer ring separator 30 covers the negative electrode sheet 10.

[0104] In one embodiment, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 745 - 750 mm; for example, the length of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 745 mm, 746 mm, 747 mm, 748 mm, 749 mm, 750 mm, or any value between any two of the above numerical ranges. The width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 20 - 25 mm; for example, the width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, or any value between any two of the above numerical ranges. The length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 800 - 805 mm; for example, the length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 800 mm, 801 mm, 802 mm, 803 mm, 804 mm, 805 mm, or any value between any two of the above numerical ranges. The width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 20 - 25 mm; for example, the width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, or any value between any two of the above numerical ranges. The capacity ratio (N / P ratio) of the positive electrode tab 20 and the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1.2 - 1.4. The lengths of the negative electrode tab 10 and the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention satisfy the case-fitting dimensions of the 13300 model battery, where the outer dimensions of the cylindrical battery 100 corresponding to 13300 are a diameter of 13 mm and a height of 300 mm. The cylindrical battery 100 provided by the present invention has a battery capacity of 580 - 700 mAh at a discharge rate of 0.2C.

[0105] In one embodiment, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 745-750 mm; for example, the length of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 745 mm, 746 mm, 747 mm, 748 mm, 749 mm, 750 mm, or any value between any two of the above numerical ranges. The width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 25-30 mm; for example, the width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, or any value between any two of the above numerical ranges. The length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 800-805 mm; for example, the length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 800 mm, 801 mm, 802 mm, 803 mm, 804 mm, 805 mm, or any value between any two of the above numerical ranges. The width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 25-30 mm; for example, the width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, or any value between any two of the above numerical ranges. The capacity ratio (N / P ratio) of the positive electrode tab 20 and the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1.2-1.4. The lengths of the negative electrode tab 10 and the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention satisfy the case-fitting dimensions of the 13350 model battery, where the outer dimensions of the cylindrical battery 100 corresponding to 13350 are a diameter of 13 mm and a height of 350 mm. The cylindrical battery 100 provided by the present invention has a battery capacity of 710-810 mAh at a discharge rate of 0.2C.

[0106] In one embodiment, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 745 - 750 mm; for example, the length of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 745 mm, 746 mm, 747 mm, 748 mm, 749 mm, 750 mm, or any value between any two of the above numerical ranges. The width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 30 - 35 mm; for example, the width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, or any value between any two of the above numerical ranges. The length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 800 - 805 mm; for example, the length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 800 mm, 801 mm, 802 mm, 803 mm, 804 mm, 805 mm, or any value between any two of the above numerical ranges. The width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 30 - 35 mm; for example, the width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, or any value between any two of the above numerical ranges. The capacity ratio (N / P ratio) of the positive electrode tab 20 and the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1.2 - 1.4. The lengths of the negative electrode tab 10 and the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention satisfy the case-fitting dimensions of the 13400 model battery, where the outer dimensions of the cylindrical battery 100 corresponding to 13400 are a diameter of 13 mm and a height of 400 mm. The cylindrical battery 100 provided by the present invention has a battery capacity of 820 - 920 mAh at a discharge rate of 0.2C.

[0107] In one embodiment, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 1300 - 1320 mm; for example, the length of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 1300 mm, 1305 mm, 1310 mm, 1315 mm, 1320 mm, or any value between any two of the above numerical ranges. The width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 25 - 35 mm; for example, the width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 25 mm, 27 mm, 29 mm, 31 mm, 33 mm, 35 mm, or any value between any two of the above numerical ranges. The length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 1360 - 1380 mm; for example, the length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 1360 mm, 1365 mm, 1370 mm, 1375 mm, 1380 mm, or any value between any two of the above numerical ranges. The width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 25 - 35 mm; for example, the width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 25 mm, 27 mm, 29 mm, 31 mm, 33 mm, 35 mm, or any value between any two of the above numerical ranges. The capacity ratio (N / P ratio) of the positive electrode tab 20 and the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1.2 - 1.4. The lengths of the negative electrode tab 10 and the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention satisfy the shell-fitting dimensions of the 18350 model battery, where the outer shell dimensions of the cylindrical battery 100 corresponding to 18350 are a diameter of 18 mm and a height of 350 mm. The cylindrical battery 100 provided by the present invention has a battery capacity of 1000 - 1600 mAh at a discharge rate of 0.2C.

[0108] In one embodiment, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 1300 - 1320 mm; for example, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 1300 mm, 1305 mm, 1310 mm, 1315 mm, 1320 mm, or any value between any two of the above numerical ranges. The width of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 40 - 45 mm; for example, the width of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 40 mm, 41 mm, 42 mm, 43 mm, 44 mm, 45 mm, or any value between any two of the above numerical ranges. The length of the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1360 - 1380 mm; for example, the length of the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1360 mm, 1365 mm, 1370 mm, 1375 mm, 1380 mm, or any value between any two of the above numerical ranges. The width of the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 40 - 45 mm; for example, the width of the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 40 mm, 41 mm, 42 mm, 43 mm, 44 mm, 45 mm, or any value between any two of the above numerical ranges. The capacity ratio (N / P ratio) of the positive electrode tab 20 and the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1.2 - 1.4. The lengths of the negative electrode tab 10 and the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention satisfy the case-fitting dimensions of the 18500 model battery, where the outer dimensions of the cylindrical battery 100 corresponding to 18500 are a diameter of 18 mm and a height of 500 mm. The cylindrical battery 100 provided by the present invention has a battery capacity of 2100 - 2400 mAh at a discharge rate of 0.2C.

[0109] In one embodiment, the length of the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention is 1300 - 1320 mm; for example, the length of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 1300 mm, 1305 mm, 1310 mm, 1315 mm, 1320 mm, or any value between any two of the above numerical ranges. The width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 50 - 55 mm; for example, the width of the positive electrode tab 20 of the cylindrical battery 100 provided by the present invention is 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, or any value between any two of the above numerical ranges. The length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 1360 - 1380 mm; for example, the length of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 1360 mm, 1365 mm, 1370 mm, 1375 mm, 1380 mm, or any value between any two of the above numerical ranges. The width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 50 - 55 mm; for example, the width of the negative electrode tab 10 of the cylindrical battery 100 provided by the present invention is 50 mm, 51 mm, 52 mm, 53 mm, 54 mm, 55 mm, or any value between any two of the above numerical ranges. The capacity ratio (N / P ratio) of the positive electrode tab 20 and the negative electrode tab 10 in the cylindrical battery 100 provided by the present invention is 1.2 - 1.4. The lengths of the negative electrode tab 10 and the positive electrode tab 20 in the cylindrical battery 100 provided by the present invention satisfy the casing size of the 18600 model battery, and the outer casing size of the cylindrical battery 100 corresponding to 18600 is a diameter of 18 mm and a height of 600 mm. The cylindrical battery 100 provided by the present invention has a battery capacity of 2500 - 2900 mAh at a discharge rate of 0.2C.

[0110] In addition, the present invention also provides an electronic cigarette, including the above-mentioned cylindrical battery 100. The cylindrical battery 100 has a high energy density. Using this cylindrical battery 100 can extend the usage time of the electronic cigarette and reduce frequent charging. The cylindrical battery 100 in the present invention has a high voltage platform, which helps to ensure a consistent amount of smoke and taste during the use of the electronic cigarette, improve the user experience, help the electronic cigarette product to have excellent performance, and enhance the market competitiveness.

[0111] The present invention will be further described in detail below with reference to embodiments and comparative examples:

[0112] The embodiments of the present application will be described below. The facts described below are exemplary and are only used to explain the present application and should not be construed as a limitation of the present application. For technologies or conditions not specified in the embodiments, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product specifications. For reagents or components whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0113] I. Cylindrical battery 100

[0114] Embodiment 1

[0115] (1) Preparation of the negative electrode sheet 10:

[0116] Using micron-sized pure silicon particles as the negative electrode silicon-based active material, mixing and stirring evenly with binder PAA, binder PAM, conductive agent CNT, conductive agent SP, and conductive agent RGO in deionized water according to a mass ratio of 91:0.8:1.7:1:2:2 to make a negative electrode slurry, and double-sided coating it on the surface of a copper foil with a thickness of 6 μm and a length of 803 mm at a surface density of 1.9 mg / cm 2 The coating length is 784 mm, and the length of the blank area at one end is 7 mm. A 12-mm blank area is left in the middle position of the positive length direction of the negative electrode sheet 10. After cold pressing and cutting into a pole piece with a width of 24 mm, a thickness of 21 μm, and a length of 803 mm, after welding the tab at the 12-mm blank area in the middle position of the positive length direction of the negative electrode sheet 10, the negative electrode sheet 10 with the negative electrode silicon-based active material attached to the surface is obtained. The specific capacity of the negative electrode silicon-based active material in the negative electrode sheet 10 is 3600 mAh / g.

[0117] (2) Preparation of the positive electrode sheet 20:

[0118] Using lithium cobaltate (LCO) as the positive electrode active material, mixing and stirring evenly with binder polytetrafluoroethylene (PVDF) and conductive agents SP and MWCNT in N-methylpyrrolidone (NMP) according to a mass ratio of 96:1.14:1.5:1.09 to make a positive electrode slurry, and double-sided coating the positive electrode slurry on an aluminum foil with a thickness of 12 μm and a length of 748 mm at a surface density of 28 mg / cm 2 The length of the blank area at one end is 10 mm. A 48-mm blank area is left in the middle position of the positive length direction of the positive electrode sheet 20. After cold pressing and cutting into a positive electrode sheet 20 with a width of 23 ± 1 mm, a thickness of 81 μm, and a length of 748 mm, and welding the positive electrode tab 22 in the blank area in the middle position of the positive length direction of the positive electrode sheet 20, the positive electrode sheet 20 with the positive electrode active material attached to the surface is obtained.

[0119] (3) Preparation of the separator 30

[0120] Select a separator 30 with a thickness of 16 μm, made of a three-layer ceramic / polyethylene (PE) / ceramic separator, with a length of 1850 mm and a width of 27 mm.

[0121] (4) Preparation of the electrolyte

[0122] In a glove box filled with argon (moisture < 10 ppm, oxygen content < 10 ppm), diethyl carbonate (DEC), propylene carbonate (PC), ethylene carbonate (EC), and fluoroethylene carbonate (FEC) are mixed in a mass ratio of DEC:PC:EC:FEC = 45:21:11:3 to obtain an organic solvent. Then, the lithium salt LiPF 6 is dissolved in the mixed organic solvent to prepare a solution with a lithium salt concentration of 1.0 mol / L. After that, vinylene sulfate (DTD), adiponitrile (ADN), and 1,3 - propanesultone (PST) are added, and the mixture is stirred evenly to obtain the electrolyte.

[0123] (5)Assembly of the cylindrical battery 100

[0124] (a): Put the prepared negative electrode sheet 10 and positive electrode sheet 20 into a vacuum oven to bake and remove water.

[0125] (b): Stack the baked negative electrode sheet 10, positive electrode sheet 20, and separator 30 in the order of "separator 30 / negative electrode sheet 10 / separator 30 / positive electrode sheet 20" and then wind them into a cylindrical winding core. When winding, first wind the side without a side of the negative electrode sheet 10, and at the same time ensure that the coated surface of the negative electrode sheet 10 completely wraps the coated surface of the positive electrode sheet 20.

[0126] (c): Punch the aluminum plastic film according to the ratio of the diameter of the cylindrical winding core to the inner diameter of the aluminum plastic film pit depth of 0.98, and put the cylindrical winding core into the pit of the aluminum plastic shell 40.

[0127] (d): Hot - press the two sides of the positive and negative electrode tabs of the aluminum plastic shell 40 at 180 - 290 °C and 0.4 - 0.6 MPa for 3 - 6 s to make the tab sealing strength > 30 N and the aluminum plastic shell 40 sealing strength > 100 N.

[0128] (e): Bake the semi - finished battery core, inject 1.67 g of the electrolyte according to the liquid injection process, seal and soak it, and then charge and form it.

[0129] (f): Trim the edges of the formed battery core, and perform secondary sealing at a vacuum degree of - 90 KPa, a sealing head temperature of 200 - 220 °C, and a sealing head pressure of 0.4 - 0.5 MPa to make the packaging strength > 100 N.

[0130] (g): Fold the edges, fold the tabs, and stick the glue to the battery core after secondary sealing according to the packaging process to obtain a finished 13300 - type battery core.

[0131] Examples 2 - 5:

[0132] Examples 2 - 5 are used to illustrate the cylindrical battery 100 of other model 13300 of the present invention, including most of the operations in Example 1, with the differences being: in Examples 2 - 4, the negative electrode active materials of the cylindrical battery 100 are different. When silicon-carbon and graphite materials are used as the silicon-based negative electrode active materials, due to the different contents of silicon-carbon or graphite in the silicon-based negative electrode active materials, the mass percentage content of silicon element in the silicon-based negative electrode active materials is different. The specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0133] Comparative Examples 1 - 3:

[0134] Comparative Examples 1 - 3 are used to comparatively illustrate the cylindrical battery 100 of model 13300, including most of the operations in Example 1, with the differences being: in Comparative Examples 1 - 3, the selection of materials in the silicon-based negative electrode active materials is different, resulting in different mass percentage contents of silicon element in the silicon-based negative electrode active materials. The specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0135] Examples 6 - 10:

[0136] Examples 6 - 10 are used to illustrate the cylindrical battery 100 of model 13400 of the present invention, including most of the operations in Example 1, with the differences being: in Examples 6 - 10, the average particle sizes of the negative electrode active materials are different. The specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0137] Examples 11 - 16:

[0138] Examples 11 - 16 are used to illustrate the cylindrical battery 100 of model 13350 of the present invention, including most of the operations in Example 1, with the differences being: in Examples 11 - 16, the coating surface density of the negative electrode tab 10 is different, resulting in different layer thicknesses of the negative electrode tab 10. The specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0139] Examples 17 - 23:

[0140] Examples 17 - 23 are used to illustrate the cylindrical battery 100 of model 18600 of the present invention, including most of the operations in Example 1, with the differences being: in Examples 17 - 23, the compaction density of the silicon-based negative electrode active materials is different, resulting in different layer thicknesses of the negative electrode tab 10. The specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0141] Examples 24 - 25:

[0142] Examples 24 - 25 are used to illustrate the cylindrical battery 100 of the 18350 model of the present invention, including most of the operations in Example 1, with the difference being: the different positive active materials in Examples 24 - 25, and the specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0143] Examples 26 - 30:

[0144] Examples 26 - 30 are used to illustrate the cylindrical battery 100 of the 18500 model of the present invention, including most of the operations in Example 1, with the difference being: the different average particle sizes of the positive active materials in Examples 26 - 30, and the specific parameters are subject to the data shown in Table 1 for the corresponding examples.

[0145] Table 1 Parameter table of Examples 1 - 30 and Comparative Examples 1 - 3

[0146]

[0147] II. Performance testing of the cylindrical battery 100 obtained by the above preparation method

[0148] (1) 0.2C discharge test method and battery capacity test

[0149] Under the condition of an ambient temperature of 25°C, charge at a rate of 0.2C to 4.35V, then charge at a constant voltage until the battery is full, after standing for 30 minutes, discharge at a rate of 0.2C to 2.5V, record the discharge temperature rise and capacity performance, and record the discharge capacity as the nominal capacity of the battery cell.

[0150] (2) 3A discharge test method

[0151] Under the condition of an ambient temperature of 25°C, charge at a rate of 0.2C to 4.35V, then charge at a constant voltage until the battery is full, after standing for 30 minutes, discharge at a current of 3A to 2.5V, record the discharge temperature rise and capacity performance.

[0152] (3) 6A discharge test method

[0153] Under the condition of an ambient temperature of 25°C, charge at a rate of 0.2C to 4.35V, then charge at a constant voltage until the battery is full, after standing for 30 minutes, discharge at a current of 6A to 2.5V, record the discharge temperature rise and capacity performance.

[0154] (4) 8A discharge test method

[0155] Under the condition of an ambient temperature of 25°C, charge at a rate of 0.2C to 4.35V, then charge at a constant voltage until the battery is full, after standing for 30 minutes, discharge at a current of 8A to 2.5V, record the discharge temperature rise and capacity performance.

[0156] III. Analysis of Test Results of Each Example and Comparative Example

[0157] Prepare the cylindrical batteries 100 of each example and comparative example respectively according to the above method, and measure various performance parameters. The results are shown in Table 2 below.

[0158] Table 2 Test Results of Examples 1 - 30 and Comparative Examples 1 - 3

[0159]

[0160] As can be seen from Example 1, for the 13300 model cylindrical battery 100, when the proportion of pure silicon in the negative silicon-based active material is 100%, the negative active material is pure silicon particles with a size of 3.5 μm, and the areal density of the negative electrode sheet 10 is 1.9 mg / cm 2 , and the tap density is 1.27 g / cm 3 , the thickness of the active material coating on the negative electrode sheet 10 is 15 μm, that is, the sum of the thicknesses of the first coating surface 111 and the second coating surface 112 on the upper and lower surfaces of the negative current collector 11 is controlled between 12 μm and 20 μm. At the same time, when the positive active material is lithium cobaltate with a size of 5.0 μm, under these parameters, the capacity of the battery is 650 mAh, that is, at a discharge rate of 0.2C, the capacity of the 13300 model cylindrical battery 100 is between 580 - 700 mAh. The capacity retention rate of this battery at a discharge rate of 3A is 98%, and the temperature rise reaches 16.9 °C; at discharge rates of 6A and 8A, the capacity retention rate of the battery drops below 90%, and the temperature rise also increases significantly. This is mainly because as the discharge rate increases, the discharge current increases, more heat is generated, and the time for the battery to dissipate heat to the external environment decreases, making it difficult for the heat generated inside the battery to be quickly dissipated, resulting in an increase in the battery temperature. At the same time, the electrochemical reaction rate inside the battery increases accordingly, and the polarization effect inside the battery is enhanced. The polarization effect will hinder the migration of lithium ions, resulting in a decrease in the capacity of the battery. Comparing the data of different models of cylindrical batteries 100 in Table 2, they all conform to the above variation law.

[0161] From Examples 1-5 and Comparative Examples 1-3, it can be seen that as the proportion of pure silicon in the negative silicon-based active material gradually decreases, the capacity of the cylindrical battery 100 of model 13300 shows a gradually decreasing trend. This is mainly because pure silicon has an extremely high theoretical specific capacity, far higher than that of traditional graphite. The decrease in the proportion of pure silicon in the silicon-based material will lead to a decrease in the specific capacity of the overall negative active material, thereby causing the capacity of the battery to gradually decrease. From Example 2, it can be seen that when the proportion of pure silicon is 95%, the capacity of the battery is 630 mAh, slightly lower than that of Example 1. However, at discharge rates of 6 A and 8 A, the capacity retention rate of the battery is relatively high. This is mainly because the negative active material contains a small amount of graphite, and the rate performance of graphite is better than that of pure silicon particles. The combination of the two active materials is beneficial to improving the rate performance of the battery and increasing the capacity retention rate. Combining Examples 2-5, it can be seen that when a small amount of graphite is combined with pure silicon particles or silicon-carbon materials as the negative active material of the battery, the battery has a high energy density and excellent rate performance. From Comparative Examples 1-3, it can be seen that when the proportion of graphite or silicon-carbon material in the negative active material is relatively high, although the rate performance of the battery has a certain improvement, since the specific capacity of graphite and silicon-carbon material is lower than that of pure silicon, this will to a certain extent affect the energy density of the entire negative electrode material. Therefore, the capacity of the battery is lower than 600 mAh.

[0162] From Examples 6-10, it can be seen that for the cylindrical battery 100 of model 13400, it is mainly the adjustment of the average particle size of the pure silicon particles in the negative active material. It can be seen from the table that when the average particle size of the pure silicon particles is between 3.0 - 6.5 μm, the capacity of the cylindrical battery 100 of model 13400 in Examples 6-8 is above 820 mAh. However, as the average particle size increases, the battery capacity gradually decreases. This is because when the particle size of the negative electrode material increases, the effective surface area decreases, and the contact area between the electrode and the electrolyte also decreases, resulting in a decrease in the battery capacity. Under high-rate discharge conditions, the capacity retention rate of the battery gradually decreases as the average particle size of the pure silicon particles increases, while the temperature rise inside the battery gradually increases. This is mainly because during the lithium insertion and extraction processes of large-particle-size pure silicon particles, due to the large volume change, mechanical stress and thermal effects are more likely to occur. On the one hand, this will accelerate the heat accumulation inside the battery and increase the battery temperature. On the other hand, it may also cause the particles to crack and pulverize. After pulverization, the electrical contact between the silicon particles and the current collector becomes poor, resulting in a decrease in the utilization rate of the active material, thereby causing the capacity retention rate of the battery to decrease. Therefore, selecting pure silicon particles with an average particle size of 3.0 - 6.0 μm helps to keep the battery performance more stable.

[0163] From Examples 11-16, it can be seen that for the cylindrical battery 100 of model 13350, it is mainly the adjustment of the surface density of the negative electrode sheet 10. It can be seen from Table 1 that when the surface density of the negative electrode sheet 10 is between 1.6 - 2.4 mg / cm 2When adjusted within the range, the capacity of the cylindrical battery 100 of model 13350 is above 710 mAh. As the surface density of the negative electrode tab 10 increases, the coating thickness of the negative electrode tab 10 gradually increases, but is controlled between 12 μm and 20 μm. This is mainly because as the coating thickness of the negative electrode tab 10 increases, more active materials can be utilized, which can increase the lithium storage capacity of the battery to a certain extent, thus facilitating the improvement of the battery capacity. As can be seen from Example 15, when the surface density of the negative electrode tab 10 is 1.6 mg / cm 2 At this time, a lower surface density means less active material in the mass per unit area, and the number of lithium ions that can be stored and released during the charge and discharge process is limited. Therefore, the battery has the lowest capacity. As can be seen from Example 16, when the surface density of the negative electrode tab 10 is 2.4 mg / cm 2 At this time, a higher surface density means that more negative electrode active materials are loaded on the same area, but the increase in surface density will also increase the thickness of the negative electrode tab 10 and increase the internal resistance of the battery, thus affecting the rate performance of the battery and also limiting the improvement of the battery capacity to a certain extent.

[0164] As can be seen from Examples 17 - 23, for the cylindrical battery 100 of model 18600, it is mainly the adjustment of the compaction density of the negative electrode tab 10. It can be seen from the table that when the compaction density of the negative electrode tab 10 is adjusted within the range of 1.10 - 1.30 g / cm 3 the battery capacity of the cylindrical battery 100 of model 18600 is above 2500 mAh. As can be seen from Examples 19 - 21, as the compaction density of the negative electrode tab 10 increases, the coating thickness of the negative electrode tab 10 gradually decreases, but is controlled between 12 μm and 20 μm. As the thickness of the negative electrode tab 10 decreases, under the condition of constant battery volume, the length of the negative electrode tab 10 increases, so the battery capacity gradually increases. Examples 17 - 19 and Examples 21 - 23 are the test results of the batteries corresponding to the negative electrode tabs 10 with different thicknesses at the compaction densities of 1.10 g / cm 3 and 1.30 g / cm 3 respectively. As the thickness of the negative electrode tab 10 decreases, the capacity of the battery cell shows a downward trend, which is mainly due to the influence of surface density adjustment.

[0165] As can be seen from Examples 24-25, for the 18350 cylindrical battery 100, it is mainly the adjustment of the positive electrode active material. Due to the special requirements of the e-cigarette industry for high voltage and high rate of the battery, for example, lithium iron phosphate and ternary materials are restricted to a certain extent in large-scale applications because of their lower voltage. From the test results of Examples 24-25, when the negative electrode is pure silicon and the positive electrode is made of lithium cobaltate or lithium manganate, the battery capacity is between 1000-1450 mAh. Since lithium manganate has a lower theoretical capacity compared with lithium cobaltate, the corresponding battery capacity is also lower. Lithium cobaltate has excellent rate performance, and its capacity retention rate during high-rate discharge is relatively high. Lithium manganate performs poorly under high-rate discharge conditions, mainly because the battery temperature rise is relatively high under high-rate discharge conditions, resulting in the dissolution of manganese ions, which seriously affects the rate performance of the battery.

[0166] As can be seen from Examples 26-30, for the 18500 cylindrical battery 100, it is mainly the adjustment of the average particle size of the positive electrode active material. As can be seen from the table, when the average particle size of the positive electrode material lithium cobaltate is between 4.5-6.5 μm, the capacity of the 18500 cylindrical battery 100 in Examples 26-30 is 2250 mAh. This is mainly because the average particle size of general high-voltage lithium cobaltate may reach the range of 16 μm - 20 μm, and the average particle size of the lithium cobaltate used in the present invention is between 4.5-6.5 μm. The relatively small volume change of the positive electrode material with a smaller particle size during charge and discharge is helpful to maintain the stability of the battery performance, so the impact on the battery capacity is relatively small. As can be seen from Example 28, when the particle size of the positive electrode material lithium cobaltate is greater than 6.0 μm, the rate performance of the battery gradually decreases. This is because as the particle size of the positive electrode material increases, the diffusion path of lithium ions inside the material becomes longer, and the diffusion resistance also increases accordingly. This will cause the transmission rate of lithium ions during charge and discharge to slow down, thus affecting the rate performance of the battery. Therefore, selecting lithium cobaltate particles with an average particle size of 4.5-6.0 μm is helpful to keep the battery performance more stable.

[0167] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A negative electrode plate, characterized in that: It includes a negative electrode current collector, a negative electrode tab arranged on the negative electrode current collector, and a negative electrode silicon-based active material; The negative electrode silicon-based active material comprises pure silicon particles, and the mass percentage of the pure silicon particles in the negative electrode silicon-based active material is 65-100%; The double-sided surface density of the negative electrode plate is 1.6-2.4 mg / cm²; the compaction density of the negative electrode plate is 1.1-1.3 g / cm³; The negative electrode silicon-based active material forms a first coating surface and a second coating surface on the upper and lower surfaces of the negative electrode current collector, respectively. The sum of the thicknesses of the first coating surface and the second coating surface is 12 μm-20 μm.

2. A negative electrode sheet according to claim 1, characterized in that: The gram capacity of the pure silicon particles is ≥3200 mAh / g.

3. A negative electrode sheet as claimed in claim 2, characterized in that: The average particle size of the pure silicon particles is 3.0-6.0 μm.

4. A negative electrode sheet according to claim 1, characterized in that: The thickness of the negative electrode plate is 18 μm-28 μm.

5. A negative electrode sheet according to claim 1, characterized in that: The first coated surface and the second coated surface respectively include two negative electrode coating areas, and the negative electrode tab is welded in a first blank area between the two negative electrode coating areas of the first coated surface, or the negative electrode tab is welded in a second blank area between the two negative electrode coating areas of the second coated surface.

6. A negative electrode sheet as claimed in claim 5, characterized in that: The distance between the two coating areas is 2-8 times the width of the negative electrode tab.

7. A negative electrode sheet as claimed in claim 5, characterized in that: The welding area between the negative electrode tab and the negative electrode sheet is greater than 8 mm 2 .

8. A method for preparing a negative electrode sheet according to any one of claims 1 to 7, characterized in that: The following steps are involved: A. The pure silicon particle material, the conductive agent and the binder are evenly dispersed in a solvent to obtain a negative electrode coating slurry, wherein the solid content of the negative electrode coating slurry is 10-15wt%, and the viscosity of the negative electrode coating slurry is 4000-15000mPa·s; B. The negative electrode coating slurry is coated on the surface of the current collector, and the negative electrode sheet is obtained after drying and rolling.

9. A cylindrical battery, characterized in that: It comprises an aluminum-plastic shell, an electrolyte placed in the shell and a cylindrical winding core, wherein the cylindrical winding core comprises a positive electrode sheet, a separator and a negative electrode sheet as described in any one of claims 1 to 7.

10. A cylindrical battery as claimed in claim 9, characterized in that: The positive electrode plate comprises a positive electrode current collector, a positive electrode tab disposed on the positive electrode current collector, and a positive electrode active material, wherein the positive electrode active material is one of lithium manganese oxide or lithium cobalt oxide.

11. A cylindrical battery as claimed in claim 10, characterized in that: The proportion of lithium cobalt oxide in the positive electrode active material is 80-100wt%.

12. A cylindrical battery as claimed in claim 11, characterized in that: The average particle size of the lithium cobalt oxide is 4.5-6.0 μm.

13. A cylindrical battery as claimed in claim 10, characterized in that: The positive electrode active material forms a third coating surface and a fourth coating surface on the upper and lower surfaces of the positive electrode current collector, respectively; the third coating surface and the fourth coating surface respectively include two positive electrode coating areas, and the positive electrode tab is welded in a third blank area between the two positive electrode coating areas of the third coating surface, or the positive electrode tab is welded in a fourth blank area between the two positive electrode coating areas of the fourth coating surface.

14. A cylindrical battery as claimed in claim 13, characterized in that: The length of the positive electrode plate is 745-750mm and the width is 20-25mm; the length of the negative electrode plate is 800-805mm and the width is 20-25mm; the cylindrical battery has a battery capacity of 580-700mAh at a discharge rate of 0.2C.

15. A cylindrical battery as claimed in claim 13, characterized in that: The length of the positive electrode plate is 745-750mm and the width is 25-30mm; the length of the negative electrode plate is 800-805mm and the width is 25-30mm; the cylindrical battery has a battery capacity of 710-810mAh at a discharge rate of 0.2C.

16. A cylindrical battery as claimed in claim 13, characterized in that: The length of the positive electrode plate is 745-750mm and the width is 30-35mm; the length of the negative electrode plate is 800-805mm and the width is 30-35mm; the cylindrical battery has a battery capacity of 820-920mAh at a discharge rate of 0.2C.

17. A cylindrical battery as claimed in claim 13, characterized in that: The length of the positive electrode plate is 1300-1320mm and the width is 25-35mm; the length of the negative electrode plate is 1360-1380mm and the width is 25-35mm; the cylindrical battery has a battery capacity of 1000-1600mAh at a discharge rate of 0.2C.

18. A cylindrical battery as claimed in claim 13, characterized in that: The length of the positive electrode plate is 1300-1320mm and the width is 40-45mm; the length of the negative electrode plate is 1360-1380mm and the width is 40-45mm; the cylindrical battery has a battery capacity of 2100-2400mAh at a discharge rate of 0.2C.

19. A cylindrical battery as claimed in claim 13, characterized in that: The length of the positive electrode plate is 1300-1320mm and the width is 50-55mm; the length of the negative electrode plate is 1360-1380mm and the width is 50-55mm; the cylindrical battery has a battery capacity of 2500-2900mAh at a discharge rate of 0.2C.

20. An electronic cigarette, characterized in that: Comprising a cylindrical battery as described in any one of claims 9-19.

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