A cylindrical 18650 high-capacity fast-charging lithium-ion battery and its manufacturing process

Abstract

This invention provides a cylindrical 18650 high-capacity fast-charging lithium-ion battery and its manufacturing process, comprising: a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, a gasket, and a capped steel shell; the current collector of the positive electrode sheet is a high-tensile aluminum foil with a tensile strength ≥280MPa; the positive electrode sheet consists of 96.0-98.0% positive electrode active material, 0.4-0.5% first conductive agent, 0.4-0.6% second conductive agent, 0.4-0.6% third conductive paste, and 1.1-1.3% binder. It is prepared with 0.2-0.3% lithium carbonate, and the positive electrode active material is lithium nickel cobalt manganese oxide. The negative electrode sheet is made by coating the surface of a copper foil current collector with a negative electrode slurry. The negative electrode slurry is prepared with 87.0-90.0% artificial graphite, 5.0-7.0% silicon-carbon material, 0.5-0.7% first conductive agent, 0.05-0.08% fourth conductive slurry, 1.0-1.5% dispersant, 2.0-3.0% binder, and 0.1-0.3% liquid retainer. This cylindrical 18650 high-capacity fast-charging lithium-ion battery and its preparation process effectively solve the defects of existing 18650 batteries, such as low capacity, weak fast charging, poor cycle life, insufficient high-temperature performance, silicon-carbon negative electrode expansion, interface instability, and high-rate temperature rise.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and more specifically, to a cylindrical 18650 high-capacity fast-charging lithium-ion battery and its manufacturing process. Background Technology

[0002] With the rapid development of technology, various electronic devices are placing increasingly higher demands on battery performance. 18650 cylindrical lithium-ion batteries, due to their excellent versatility and high energy density, are widely used in laptops, power banks, power tools, and electric vehicles. However, traditional 18650 lithium-ion batteries have significant limitations in charging speed, making it difficult to meet users' urgent needs for fast charging. During charging, complex electrochemical reactions occur inside the battery, and excessive charging current can easily lead to severe battery overheating and intensified polarization, thus affecting battery life and safety. To achieve fast charging, innovation and optimization are needed in battery material selection, structural design, and manufacturing processes.

[0003] Currently, the specific capacity of high-end graphite has reached 360-365 mAh / g, making the search for a negative electrode material with even higher specific capacity urgent. Silicon (theoretically with a specific capacity as high as 4200 mAh / g) is considered one of the most promising negative electrode materials for next-generation lithium-ion batteries. However, during cycling, silicon negative electrode materials experience volume expansion (>300%) and silicon particle breakage, leading to increased internal resistance and reduced capacity in lithium-ion batteries.

[0004] Therefore, there is an urgent need to develop a new cylindrical 18650 high-capacity fast-charging lithium-ion battery and its fabrication process. By optimizing the material system, interface design and fabrication process, a synergistic improvement in high energy density, excellent fast-charging performance and long cycle life can be achieved to solve the defects of existing technologies. Summary of the Invention

[0005] The present invention aims to solve the technical problems mentioned in the background art and provide a cylindrical 18650 high-capacity fast-charging lithium-ion battery and its preparation process.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a cylindrical 18650 high-capacity fast-charging lithium-ion battery, comprising: a positive electrode, a negative electrode, a separator, an electrolyte, a gasket, and a capped steel shell; The current collector of the positive electrode is a high-tensile aluminum foil with a tensile strength ≥280MPa. The positive electrode is prepared from 96.0-98.0% positive electrode active material, 0.4-0.5% first conductive agent, 0.4-0.6% second conductive agent, 0.4-0.6% third conductive paste, 1.1-1.3% binder and 0.2-0.3% lithium carbonate. The positive electrode active material is lithium nickel cobalt manganese oxide active material. The negative electrode sheet is made by coating a negative electrode slurry onto the surface of a copper foil current collector. The negative electrode slurry is prepared from 87.0-90.0% artificial graphite, 5.0-7.0% silicon carbide, 0.5-0.7% first conductive agent, 0.05-0.08% fourth conductive slurry, 1.0-1.5% dispersant, 2.0-3.0% binder, and 0.1-0.3% liquid retainer. The separator is a single-sided ceramic-coated separator with polypropylene or polyethylene as the base material, and the ceramic-coated side of the separator faces the positive electrode plate. The battery adopts a positive electrode monotab and a negative electrode bitab structure. The positive electrode monotab is an aluminum electrode, and the negative electrode bitab is a copper-nickel composite electrode.

[0007] Furthermore, the thickness of the positive electrode sheet is 140-143 μm, and the compaction density of the positive electrode sheet is 3.40-3.45 g / cm³.

[0008] Furthermore, the thickness of the negative electrode sheet is 139-142 μm, and the compaction density of the negative electrode sheet is 1.59-1.63 g / cm³.

[0009] Furthermore, the first conductive agent is Li-435, the second conductive agent is KS6, the third conductive paste is 108A-44, and the fourth conductive paste is SWCNT single-walled carbon nanotubes; the liquid retaining agent is SFC3100, and the binder is PAA aqueous binder.

[0010] Furthermore, the total thickness of the diaphragm is 9 μm, and the thickness of the ceramic coating on the diaphragm is 3 μm; the porosity of the diaphragm is 40%-45%, and the air permeability is 100-150 s / 100 mL.

[0011] Furthermore, the thickness of the high tensile aluminum foil of the positive electrode is 14-16 μm, and the thickness of the copper foil current collector of the negative electrode is 8-10 μm.

[0012] Furthermore, the battery core has a tight-wound structure with an outer diameter of 17.2-17.6mm; the battery charging cut-off voltage is 4.20±0.02V, the discharging cut-off voltage is 2.5±0.05V, the maximum continuous charging current is 1.5C, the maximum continuous discharging current is 15A, and the 10s pulse discharge current is 30A.

[0013] Furthermore, the positive electrode slurry is composed of 97-98% single-crystal small-particle lithium nickel cobalt manganese oxide, 0.4-0.5% Li-435 conductive agent, 0.4-0.5% KS6 conductive agent, 0.4-0.5% 108A-44 conductive slurry, 0.2-0.3% lithium carbonate, and 1.1-1.2% PVDF polyvinylidene fluoride by mass percentage.

[0014] Furthermore, the negative electrode slurry is composed of 87-90% artificial graphite, 6-7% silicon carbide material, 0.5-0.6% Li-435 conductive agent, 0.05-0.06% SWCNT single-walled carbon nanotubes, 1.2-1.3% CMC dispersant, 2.1-2.3% PAA aqueous binder, and 0.2-0.3% SFC liquid retainer by mass percentage.

[0015] A fabrication process for the above-described cylindrical 18650 high-capacity fast-charging lithium-ion battery includes the following steps: S1: The positive electrode slurry raw material and PVDF adhesive are mixed evenly at a solid content of 70% to prepare the positive electrode slurry. The positive electrode slurry is coated on a high tensile aluminum foil with a thickness of 14-16μm, dried at 110-130℃ and then rolled to obtain a positive electrode sheet with a thickness of 141-144μm and a compaction density of 3.40-3.44g / cm³. S2: CMC dry powder and deionized water are mixed at a solid content of 2.0% to prepare CMC adhesive solution. Conductive agent, silicon carbon material, artificial graphite and binder are mixed evenly and added to CMC adhesive solution in batches to obtain negative electrode slurry. The negative electrode slurry is coated on copper foil with a thickness of 8-10 μm, dried at 120-140℃ and then rolled to obtain a negative electrode sheet with a thickness of 139-142 μm and a compaction density of 1.60-1.64 g / cm³. S3: Cut the dried positive and negative electrode sheets into strips of the required width, weld the tabs on the sheet making machine, and apply insulating glue to the tab positions to cover the exposed current collector and the tabs; wind the positive electrode sheet, ceramic separator, and negative electrode sheet into a cylindrical core; put the core into a steel shell, connect the negative tab to the steel shell by bottom welding, and then fix the core inside the steel shell by roller groove; S4: Inject electrolyte into the steel shell, weld the cover plate to the positive electrode tab and fix it, and finally seal and clean to obtain a cylindrical 18650 high-capacity fast-charging lithium-ion battery.

[0016] The beneficial effects of this invention are: 1. First, the positive electrode material, lithium nickel cobalt manganese oxide (single-crystal small particles), can maintain grain integrity during cycling, resulting in superior cycle performance. Second, single-crystal ternary positive electrode materials have more significant advantages in terms of gas production and safety. Finally, this positive electrode material has higher specific capacity and lower cost, and the use of high-tensile aluminum foil in the positive electrode provides higher tensile strength (≥280MPa) and greater ductility, making the positive electrode sheet more flexible and less prone to brittleness. The negative electrode material uses an artificial graphite-silicon-carbon system combined with PAA aqueous binder, which can suppress the volume expansion of silicon-based negative electrode materials and improve conductivity, forming a denser and more stable structure. The SEI film reduces impedance, promotes improved cycle performance, and enhances electrochemical performance. Furthermore, the use of a liquid retainer (negative electrode additive) made of functional polymer SFC, a large-particle-size anionic polymer emulsion, offers advantages such as improved battery liquid retention, electrode wetting performance, enhanced high-temperature storage and cycling performance, and reduced battery internal resistance. The ceramic face of the positive electrode helps reduce interfacial impedance: it reduces the interfacial impedance between the positive electrode and the separator, inhibits the dissolution of positive electrode metal ions, extends cycle life, and facilitates smoother lithium ion transport between the positive electrode and the separator, thereby improving the battery's charge / discharge efficiency and overall performance. 2. A cylindrical 18650 high-capacity fast-charging lithium-ion battery made of lithium nickel cobalt manganese oxide-artificial graphite silicon carbon system, with a capacity of 3500mAh and excellent cycle performance, with ≥80% after 1000 cycles of 0.5C charge and 1C discharge at room temperature, and ≥80% after 300 cycles of 1C charge and 2C discharge at room temperature. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only drawings of some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams and are not intended to limit the actual size of the product, the actual flow of the method, the actual timing of the signals, etc. involved in the embodiments of the present invention.

[0018] Figure 1 The discharge curves of the cylindrical 18650 high-capacity fast-charging lithium-ion battery of Embodiment 1 of the present invention at discharge rates of 0.2C, 0.5C, 1C, 5A, 10A, and 15A are shown.

[0019] Figure 2 This is a cycle life diagram of a cylindrical 18650 high-capacity fast-charging lithium-ion battery under 0.5C-1C discharge at room temperature, which is the comparative example of Embodiment 1 of the present invention.

[0020] Figure 3This is a cycle life diagram of a cylindrical 18650 high-capacity fast-charging lithium-ion battery under 1C-3C discharge at room temperature, which is the comparative example of Embodiment 1 of the present invention.

[0021] Figure 4 The diagram shows the cycle life of a cylindrical 18650 high-capacity fast-charging lithium-ion battery at 45°C and 0.5C-13A discharge, which is an example of the present invention and a comparative example. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. Example

[0025] like Figures 1 to 4 As shown in the figure, the present invention provides a cylindrical 18650 high-capacity fast-charging lithium-ion battery and its manufacturing process, which includes: a positive electrode, a negative electrode, a separator, an electrolyte, a gasket, and a capped steel shell; The current collector of the positive electrode is a high-tensile aluminum foil with a tensile strength ≥280MPa. The positive electrode is made of 97.2% positive electrode active material, 0.4% first conductive agent, 0.5% second conductive agent, 0.5% third conductive paste, 1.2% binder and 0.2% lithium carbonate. The positive electrode active material is lithium nickel cobalt manganese oxide. Among them, firstly, nickel-rich materials have gradually become one of the most important positive electrode materials for electric vehicles due to their high energy and high power density. Moreover, lithium nickel cobalt manganese oxide (single crystal small particles) can maintain the integrity of the crystal grains during cycling, and the cycle performance is better. Secondly, in terms of gas production and safety, the advantages of single crystal ternary positive electrode materials are more obvious.

[0026] The negative electrode sheet is made by coating a negative electrode slurry onto the surface of a copper foil current collector. The negative electrode slurry is prepared from 89.3% artificial graphite, 6.55% silicon carbide material, 0.5% first conductive agent, 0.05% fourth conductive slurry, 1.2% dispersant, 2.2% binder and 0.2% liquid retainer. The separator is a single-sided ceramic-coated separator with polypropylene or polyethylene as the base material, and the ceramic-coated side of the separator faces the positive electrode plate. The battery adopts a positive electrode monotab and a negative electrode bitab structure. The positive electrode monotab is an aluminum electrode, and the negative electrode bitab is a copper-nickel composite electrode.

[0027] In one embodiment, the thickness of the positive electrode is 141 μm and the compaction density of the positive electrode is 3.41 g / cm³.

[0028] In one embodiment, the negative electrode sheet has a thickness of 140 μm and a compaction density of 1.60 g / cm³.

[0029] In one embodiment, the first conductive agent is Li-435, the second conductive agent is KS6, the third conductive paste is 108A-44, the fourth conductive paste is SWCNT single-walled carbon nanotubes; the liquid retention agent is SFC3100, and the binder is PAA aqueous binder. Among them, polyacrylic acid (PAA) is a highly water-based polymer that can better suppress the volume expansion of silicon-based anode materials, form a denser and more stable SEI film, reduce impedance, promote improved cycle performance, and improve electrochemical performance. Furthermore, the SFC liquid retainer is a large-particle-size anionic polymer emulsion, which has the advantages of improving the battery's liquid retention performance, electrode wetting performance, high-temperature storage, high-temperature cycling, and reducing battery internal resistance. Therefore, the positive electrode of this invention uses lithium nickel cobalt manganese oxide (single crystal particles) material, and the negative electrode uses artificial graphite, silicon carbon material, PAA water-based binder, and SFC liquid retainer to prepare a cylindrical 18650 high-capacity fast-charging lithium-ion battery with excellent cycle performance (0.5C-1C and 1C-2C at room temperature) and rate performance.

[0030] In one embodiment, the total thickness of the diaphragm is 9 μm, and the thickness of the ceramic coating on the diaphragm is 3 μm; the diaphragm porosity is 40%-45%, and the air permeability is 100-150 s / 100 mL.

[0031] In one embodiment, the thickness of the high-tensile aluminum foil of the positive electrode is 15 μm, and the thickness of the copper foil current collector of the negative electrode is 8 μm.

[0032] In one embodiment, the battery core is a tightly wound structure with an outer diameter of 17.2-17.6 mm; the battery charging cut-off voltage is 4.20±0.02V, the discharging cut-off voltage is 2.5±0.05V, the maximum continuous charging current is 1.5C, the maximum continuous discharging current is 15A, and the 10s pulse discharge current is 30A.

[0033] In one embodiment, the positive electrode slurry is composed of 97.2% single-crystal small-particle lithium nickel cobalt manganese oxide, 0.4% Li-435 conductive agent, 0.5% KS6 conductive agent, 0.5% 108A-44 conductive slurry, 0.2% lithium carbonate, and 1.2% PVDF polyvinylidene fluoride by mass percentage.

[0034] In one embodiment, the negative electrode slurry is composed of 89.5% artificial graphite, 6.55% silicon carbide material, 0.5% Li-435 conductive agent, 0.05% SWCNT single-walled carbon nanotubes, 1.2% CMC dispersant, 2.2% PAA aqueous binder, and 0.2% SFC liquid retainer by mass percentage.

[0035] A preparation and testing process for the above-mentioned cylindrical 18650 high-capacity fast-charging lithium-ion battery includes the following steps: S1. Slurry preparation: Preparation of positive electrode slurry: First, PVDF powder and NMP solvent are synthesized into PVDF liquid with a solid content of 8%. Then, Li-435 conductive agent, KS6 conductive agent and Inano-NO3-D4 conductive slurry are added to the PVDF liquid. The material is prepared into a slurry with a solid content of 70% and a viscosity of 5800 mPa s in a planetary dispersion vacuum mixer with a revolution of 20 RPM and a rotation of 1000 RPM. Negative electrode slurry preparation: First, CMC powder and water solvent are synthesized into CMC slurry with a solid content of 2%. Then, Li-435 conductive agent, SWCNT single-walled carbon nanotubes, silicon carbide and artificial graphite are stirred in a planetary dispersion vacuum mixer at 24 RPM and 1300 RPM. Finally, PAA binder and SFC liquid retainer are added and stirred in a planetary dispersion vacuum mixer at 20 Hz and 800 RPM to prepare a slurry with a solid content of 48% and a viscosity of 4000 mPa·s. S2. Coating: Using a gap extrusion coating machine, the positive electrode slurry is coated onto a 15μm thick high-tensile aluminum foil, and the negative electrode slurry is coated onto an 8μm thick copper foil to prepare a positive electrode sheet with a single-sided density of 230g / m². The oven baking temperature is 100℃, the air frequency is 38HZ, and the coating speed is 20m / min. A negative electrode sheet with a single-sided density of 90g / m² is prepared by baking at an oven temperature of 120℃, an air frequency of 42HZ, and a coating speed of 18m / min. S3. Sheet making: The dried electrode sheets are rolled on a roller press to obtain positive and negative electrode sheets with thicknesses of 141μm and 140μm respectively; then the rolled positive and negative electrode sheets are cut into strips of 57.5mm and 59mm respectively on a slitting machine, and finally placed in a vacuum drying oven to dry at 120℃ for 10h. S4. Assembly: The positive and negative electrode sheets and a 14μm ceramic diaphragm are wound into a core on a winding machine at an ambient temperature ≤23℃ and a dew point ≤-35℃. The winding tension is controlled at 1.5N・m for the positive and negative electrode sheets and 0.06-0.08MPa for the diaphragm. After passing the Hi-Pot short circuit test and appearance inspection, the cell, upper and lower insulating sheets are placed in a steel shell with a diameter of 18.4±0.1mm and a height of 65.2±0.15mm. The negative electrode tab is connected to the steel shell by spot welding. After passing a series of tests such as grooving, the electrolyte is injected. S5. Electrolyte injection: In the injection room with an ambient temperature ≤23℃ and a dew point ≤-35℃, inject 5.5±0.1g of electrolyte, vacuum and let stand until the electrolyte dries, then seal and clean it, and finally cover it with a film and let it stand at room temperature for 36 hours. S6. Formation and Capacity Testing: After standing at 60℃ for 24 hours, charge the battery to 4.2V with a constant current and constant voltage of 0.5C, cut off the current at 0.02C, stand for 10 minutes, and then discharge it with a constant current of 0.2C. Record the capacity and select qualified batteries in 30mAh increments.

[0036] This cylindrical 18650 high-capacity fast-charging lithium battery uses lithium nickel cobalt manganese oxide (a single-crystal small-particle material) as the positive electrode active material. The single-crystal particles significantly prevent the formation of intergranular cracks caused by the volume-oriented change of anisotropic stress, thereby mitigating the unintended interaction between the electrode and the electrolyte. Enhanced interfacial stability effectively prevents the irreversible phase transition from layered to rock salt phases and shortens the transport distance between lithium ions in single-crystal particles, improving the insertion and extraction kinetics of lithium ions in electrode materials. This significantly improves structural stability and cycle performance, which is beneficial for the battery's fast-charging performance, especially at high temperatures. The positive electrode uses high-tensile aluminum foil, which has higher tensile strength (≥280MPa) and higher ductility. The negative electrode uses artificial graphite / silicon-carbon as the active material. Artificial graphite has significant advantages in long cycle life, high temperature, and high rate capability. Silicon has attracted much attention due to its ultra-high specific capacity (4200mAh / g), low lithium intercalation potential (0.4V), and better safety performance. During fast charging, the lithium potential of graphite negative electrode is about 0V, so it is prone to lithium deposition. However, silicon has a higher lithium intercalation platform, with a lithium potential of about 0.5V, and the possibility of surface lithium deposition is smaller. Therefore, it can improve the fast-charging performance of the negative electrode. Safety is a concern; however, the significant volume expansion (~300%) of silicon anodes during charge and discharge greatly limits their commercialization. Silicon, being a semiconductor, has poor conductivity, which is detrimental to the effective release of battery capacity at high rates. To overcome the defects of silicon anode materials, this invention uses two conductive agents in the anode to further improve conductivity, and employs a (polyacrylic acid) PAA aqueous binder. The advantages of this binder are: PAA binder can form a coating layer (SEI film) with silicon similar to a solid electrolyte interface, maintaining electrode stability and improving the first coulombic efficiency of silicon-based anodes; it effectively blocks the corrosion of active materials by the electrolyte, reduces electrode impedance, and improves the lithium-ion diffusion rate; it significantly improves the cycle performance of silicon-based anodes. Due to its high cross-linking network and mechanical toughness, it can effectively suppress the severe volume expansion problem of silicon-based anodes. It can also be used with conductive additives to further improve the conductivity and electrochemical performance of the battery. The cylindrical 18650 high-capacity fast-charging lithium battery of the present invention can achieve a capacity of 3500mAh at a 0.2C rate and can provide excellent cycle performance. At room temperature, it can achieve ≥80% of the capacity after 1000 cycles of 0.5C charge and 1C discharge, ≥90% of the capacity after 300 cycles of 1C charge and 3C discharge, and ≥90% of the capacity after 300 cycles of 0.5C charge and 13A discharge at 45°C.

[0037] The structure, materials, formulation and process are completely consistent with those of Example 1, the only difference being that the separator coating surface of the comparative battery faces the negative electrode and the base surface faces the positive electrode.

[0038] The batteries of Example 1 and the comparative example were subjected to rate discharge, room temperature cycling, and high temperature cycling tests. The battery of Example 1 achieved a capacity of 3500mAh at 0.2C rate; after 1000 cycles of 0.5C charge-1C discharge at room temperature, the capacity retention rate was ≥80%; after 300 cycles of 1C charge-3C discharge at room temperature, the capacity retention rate was ≥90%; and after 300 cycles of 0.5C charge-13A discharge at 45℃, the capacity retention rate was ≥90%. The comparative example, due to an improperly oriented separator, had high interfacial impedance and more metal ion dissolution, resulting in a significantly lower capacity retention rate than Example 1 under the same cycling conditions. Its rate discharge performance and high temperature stability were also inferior to the solution of this invention.

[0039] The test results show that this invention effectively solves the defects of existing 18650 batteries, such as low capacity, weak fast charging, poor cycle life, insufficient high-temperature performance, silicon-carbon anode expansion, interface instability, and high-rate temperature rise, through the synergistic optimization of positive electrode single-crystal ternary material, high tensile current collector, artificial graphite silicon-carbon anode, PAA binder and SFC liquid retainer, directional arrangement of ceramic separator, tab structure and preparation process. It is suitable for large-scale industrial production and high-end fast charging application scenarios.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cylindrical 18650 high-capacity fast-charging lithium-ion battery, characterized in that, include: Positive electrode plate, negative electrode plate, separator, electrolyte, gasket and cap steel shell; The current collector of the positive electrode is a high-tensile aluminum foil with a tensile strength ≥280MPa. The positive electrode is prepared from 96.0-98.0% positive electrode active material, 0.4-0.5% first conductive agent, 0.4-0.6% second conductive agent, 0.4-0.6% third conductive paste, 1.1-1.3% binder and 0.2-0.3% lithium carbonate. The positive electrode active material is lithium nickel cobalt manganese oxide active material. The negative electrode sheet is made by coating a negative electrode slurry onto the surface of a copper foil current collector. The negative electrode slurry is prepared from 87.0-90.0% artificial graphite, 5.0-7.0% silicon carbide, 0.5-0.7% first conductive agent, 0.05-0.08% fourth conductive slurry, 1.0-1.5% dispersant, 2.0-3.0% binder, and 0.1-0.3% liquid retainer. The separator is a single-sided ceramic-coated separator with polypropylene or polyethylene as the base material, and the ceramic-coated side of the separator faces the positive electrode plate. The battery adopts a positive electrode monotab and a negative electrode bitab structure. The positive electrode monotab is an aluminum electrode, and the negative electrode bitab is a copper-nickel composite electrode.

2. The cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The thickness of the positive electrode sheet is 140-143 μm, and the compaction density of the positive electrode sheet is 3.40-3.45 g / cm³.

3. The cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The thickness of the negative electrode sheet is 139-142 μm, and the compaction density of the negative electrode sheet is 1.59-1.63 g / cm³.

4. A cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The first conductive agent is Li-435, the second conductive agent is KS6, the third conductive paste is 108A-44, and the fourth conductive paste is SWCNT single-walled carbon nanotubes; the liquid retaining agent is SFC3100, and the binder is PAA aqueous binder.

5. A cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The total thickness of the diaphragm is 9 μm, and the thickness of the ceramic coating on the diaphragm is 3 μm; the porosity of the diaphragm is 40%-45%, and the air permeability is 100-150 s / 100 mL.

6. A cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The thickness of the high tensile aluminum foil of the positive electrode is 14-16 μm, and the thickness of the copper foil current collector of the negative electrode is 8-10 μm.

7. A cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The battery core has a tight winding structure with an outer diameter of 17.2-17.6mm; the battery charging cut-off voltage is 4.20±0.02V, the discharging cut-off voltage is 2.5±0.05V, the maximum continuous charging current is 1.5C, the maximum continuous discharging current is 15A, and the 10s pulse discharge current is 30A.

8. A cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The positive electrode slurry is composed of 97-98% single-crystal small-particle nickel cobalt manganese oxide, 0.4-0.5% Li-435 conductive agent, 0.4-0.5% KS6 conductive agent, 0.4-0.5% 108A-44 conductive slurry, 0.2-0.3% lithium carbonate, and 1.1-1.2% PVDF (polyvinylidene fluoride) by mass percentage.

9. A cylindrical 18650 high-capacity fast-charging lithium-ion battery according to claim 1, characterized in that: The negative electrode slurry is composed of 87-90% artificial graphite, 6-7% silicon carbide material, 0.5-0.6% Li-435 conductive agent, 0.05-0.06% SWCNT single-walled carbon nanotubes, 1.2-1.3% CMC dispersant, 2.1-2.3% PAA aqueous binder, and 0.2-0.3% SFC liquid retainer by mass percentage.

10. A manufacturing process for a cylindrical 18650 high-capacity fast-charging lithium-ion battery according to any one of claims 1-9, characterized in that: Includes the following steps: S1: The positive electrode slurry raw material and PVDF adhesive are mixed evenly at a solid content of 70% to prepare the positive electrode slurry. The positive electrode slurry is coated on a high tensile aluminum foil with a thickness of 14-16μm, dried at 110-130℃ and then rolled to obtain a positive electrode sheet with a thickness of 141-144μm and a compaction density of 3.40-3.44g / cm³. S2: CMC dry powder and deionized water are mixed at a solid content of 2.0% to prepare CMC adhesive solution. Conductive agent, silicon carbon material, artificial graphite and binder are mixed evenly and added to CMC adhesive solution in batches to obtain negative electrode slurry. The negative electrode slurry is coated on copper foil with a thickness of 8-10 μm, dried at 120-140℃ and then rolled to obtain a negative electrode sheet with a thickness of 139-142 μm and a compaction density of 1.60-1.64 g / cm³. S3: Cut the dried positive and negative electrode sheets into strips of the required width, weld the tabs on the sheet making machine, and apply insulating glue to the tab positions to cover the exposed current collector and the tabs; wind the positive electrode sheet, ceramic separator, and negative electrode sheet into a cylindrical core; put the core into a steel shell, connect the negative tab to the steel shell by bottom welding, and then fix the core inside the steel shell by roller groove; S4: Inject electrolyte into the steel shell, weld the cover plate to the positive electrode tab and fix it, and finally seal and clean to obtain a cylindrical 18650 high-capacity fast-charging lithium-ion battery.

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