High-safety thermal-runaway-resistant ternary cylindrical lithium ion battery and preparation method thereof

Abstract

The application discloses a kind of high safety anti-thermal runaway ternary cylindrical lithium ion batteries and preparation method thereof, it is related to lithium ion battery technical field, including cylindrical shell, roll core, electrolyte, cover plate assembly and center needle, roll core is wound by positive and negative pole piece and diaphragm, positive electrode adopts multilayer composite current collector, electrolyte is solid-liquid composite semi-solid system, roll core is full tab rubbing flat structure and center is provided with elastic buffer layer, with double-sided ceramic coating diaphragm and thermoelectric separation two-way explosion-proof valve, form multidimensional collaborative safety system.Preparation is completed by high-precision coating, winding, vacuum infiltration, in-situ polymerization curing process to prepare battery.The application material, structure, process trinity optimization, under mechanical abuse condition, short-circuit current is quickly cut off, thermal runaway is blocked, and then successfully passes heavy impact, needle stick safety test, while maintaining high energy density, compatible with existing mass production line, suitable for new energy vehicles, electric tools and other high safety requirement scene.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology in cold regions, and in particular to a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery and its preparation method. Background Technology

[0002] Ternary lithium-ion batteries, with their high energy density, long cycle life, and good low-temperature performance, are widely used in new energy vehicles, power tools, and energy storage. Among them, 18650 and 21700 cylindrical batteries have become the mainstream product forms due to their high degree of standardization and high production efficiency. However, ternary materials themselves have poor thermal stability. When subjected to heavy impacts, needle penetration, or other mechanical abuse conditions, the battery is prone to electrode deformation and separator damage, leading to a direct internal short circuit between the positive and negative electrodes. This instantaneous release of a large amount of heat can trigger electrolyte combustion and material decomposition, ultimately resulting in fire and explosion. Consequently, they are difficult to pass safety tests such as UN38.3 and UL1642, severely limiting the application of ternary cylindrical batteries in high-end safety scenarios.

[0003] Existing technologies for improving the safety performance of ternary cylindrical batteries all suffer from core drawbacks: limitations of a single technical approach, poor overall synergy, and an inability to simultaneously address both safety and electrochemical performance. A detailed evaluation follows: Simple current collector structure improvement technology: Existing solutions that use composite current collectors to improve battery safety only focus on the insulation and melting characteristics of the current collector itself. They do not consider the chain problems such as stress concentration inside the battery, electrode breakage, and electrolyte thermal runaway under mechanical abuse. Furthermore, they do not work in conjunction with the electrolyte and battery structure. They can only alleviate local short circuits and cannot completely block the spread of thermal runaway. Their protection effect against strong mechanical abuse such as heavy object impact and needle penetration is extremely poor.

[0004] Electrolyte flame retardant modification technology: Existing conventional flame retardant electrolytes and solid / semi-solid electrolyte technologies either require the addition of a large amount of flame retardant, which leads to a significant decrease in battery ion conductivity, accelerated capacity decay, and shortened cycle life; or the solid electrolyte interface impedance is too high, resulting in poor compatibility. Moreover, these technologies are mostly used in pouch and prismatic batteries and cannot be adapted to 18650 / 21700 cylindrical wound structures. At the same time, they lack buffer protection design against mechanical stress, and electrolyte layer cracking and internal short circuit failure still occur after needle penetration and impact.

[0005] Battery structure optimization technology: Existing improvement solutions such as full tabs, thickened casing, and buffer structure are all single-structure reinforcements. Full tab technology only solves the problem of welding stress concentration, without a matching stress absorption structure; thickened casing only improves external impact resistance and cannot alleviate internal electrode extrusion; a single buffer layer does not form a safe synergy with the current collector and electrolyte, and still cannot solve the problem of thermal runaway after internal short circuit triggering, and the safety test pass rate still cannot meet the standards.

[0006] Diaphragm and explosion-proof component improvement technologies: Simply improving the diaphragm puncture strength and optimizing the explosion-proof valve can only delay the occurrence of thermal runaway, but cannot prevent the triggering of internal short circuits. When an internal short circuit occurs, heat will still accumulate rapidly, eventually leading to fire and explosion. Moreover, existing technologies have not achieved thermoelectric separation pressure relief design, and the pressure relief process is prone to causing secondary short circuits, resulting in fundamental loopholes in safety protection.

[0007] In summary, all existing safety improvement solutions for ternary cylindrical batteries are single-point optimizations, lacking comprehensive collaborative protection designs. They cannot solve the safety issues of mechanical abuse from the entire process of "internal short circuit cutoff, stress buffer absorption, heat propagation blocking, and directional pressure relief protection." At the same time, they generally suffer from problems such as sacrificing battery energy density, reducing electrochemical performance, poor production line adaptability, and excessive cost, and cannot meet the industrialization safety requirements of ternary 18650 / 21700 cylindrical batteries.

[0008] Therefore, there is an urgent need for a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery and its preparation method. Summary of the Invention

[0009] To address the aforementioned issues, this application proposes a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery and its preparation method. The aim is to solve the problems of low pass rates in safety tests such as heavy object impact and nail penetration for existing ternary material system 18650 and 21700 cylindrical batteries, and the inability of a single safety improvement scheme to simultaneously achieve both safety performance and energy density. The technical solution is as follows: On the one hand, this application proposes a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery, including a cylindrical shell, a core, an electrolyte, a cover plate assembly, and a center pin; The cover plate assembly is disposed above the cylindrical shell, and the bottom of the cylindrical shell is provided with a shell sealing and forming structure; The central pin is located in the center of the cylindrical shell, and its upper and lower ends are respectively connected to the cover plate assembly and the shell bottom sealing structure. The core is wound around the outer ring of the central needle; The core is composed of a sandwich-style spiral winding of a positive electrode sheet, a separator, and a negative electrode sheet; The positive electrode uses a PET-aluminum multilayer composite current collector, and the negative electrode uses a copper-based polymer composite current collector. The electrolyte is filled in a cylindrical shell.

[0010] Preferably, the core has a full-electrode flattening structure; A modified silicone rubber elastic buffer layer is provided between the center hole and the center pin of the core. The central needle has a hollow, heat-insulating structure.

[0011] Preferably, the electrolyte is a solid-liquid composite semi-solid electrolyte with boehmite nano-coated LLZO, and is formed by in-situ polymerization and solidification to form a continuous electrolyte phase; The diaphragm is a high-penetration double-sided ceramic-coated wet three-layer composite diaphragm.

[0012] Preferably, the PET-aluminum multilayer composite current collector has a thickness of 12-18 μm, with a PET layer in the middle and aluminum layers on both sides; The PET layer is 4-8μm thick, and the aluminum layer is 3-6μm thick. An alumina transition interlayer is provided between the aluminum layer and the PET layer to induce microcracks and melt them under mechanical extrusion, thereby achieving self-cutting of short-circuit current.

[0013] Preferably, the electrolyte is a solid-liquid composite semi-solid electrolyte, comprising LLZO solid electrolyte, boehmite coating layer, and liquid electrolyte; Among them, the particle size of LLZO solid electrolyte is 200-500 nm; Boehmite coating thickness 5-15 nm; Solid electrolyte content: 90wt%-95wt%; The liquid electrolyte is a fluoroethylene carbonate system, accounting for 5wt%-10wt%; After the electrolyte is polymerized in situ at 60-70℃, a dense semi-solid interface is formed, which has the ability to resist extrusion, block lithium dendrites and inhibit heat spread.

[0014] Preferably, the cover plate assembly integrates a thermoelectric separation bidirectional explosion-proof valve, which, from top to bottom, includes a shell end copper pressure sealing structure, a cover plate layer, a top insulating sealing gasket, and a cover plate manifold. The cover plate collector plate is equipped with Type of buffer protrusion.

[0015] Preferably, the two tab areas of the full tab flattening structure are laser welded to the bottom of the housing and the current collector of the cover plate; The cover plate current collector and the modified silicone rubber elastic buffer layer together form a radial and axial dual stress absorption structure.

[0016] Preferably, the diaphragm has a total thickness of 22-28 μm, a puncture strength ≥400 gf, and a heat shrinkage temperature ≥180℃; The modified silicone rubber elastic buffer layer has a thickness of 0.5-1 mm; The cylindrical shell is made of high-strength cold-rolled steel of HV180 or above, with a wall thickness of 0.30-0.35mm for 18650 and 0.35-0.40mm for 21700. The explosion-proof valve has an opening pressure of 0.8-1.2MPa.

[0017] On the other hand, this application proposes a method for preparing a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery, comprising the following steps: S1. The ternary cathode material, PVDF-HFP binder and compound conductive agent are made into a slurry and coated on the PET-aluminum composite current collector. The negative electrode slurry is coated on the copper-based polymer composite current collector. The slurry is dried, rolled and cut to control the edge burrs of the electrode sheet to ≤1μm. S2. Wind the positive electrode, negative electrode and separator into shape, control the winding tension tolerance ±5%, and flatten the full tabs on both sides of the core. S3. Inject modified silicone rubber liquid into the center hole of the core, insert the hollow heat insulation center needle and cure to form an elastic buffer layer; S4. Insert the core into the housing and complete the laser welding encapsulation; S5. Vacuum injection of solid-liquid composite semi-solid electrolyte at 45℃ and -0.08MPa, followed by immersion for 2-3 hours, and then heating to 60-70℃ for in-situ polymerization and curing. S6. The finished battery is obtained through formation and capacity testing.

[0018] Preferably, the PET-aluminum multilayer composite current collector, electrolyte, modified silicone rubber elastic buffer layer, full-tab flattening structure, high-puncture double-sided ceramic coated wet three-layer composite diaphragm, and thermoelectric separation bidirectional explosion-proof valve form a synergistic safety system, which simultaneously achieves rapid short-circuit current cutoff, thermal runaway path blocking, and mechanical stress buffering under needle puncture and heavy object impact.

[0019] Furthermore, the diaphragm has a total thickness of 22-28 μm, a puncture strength ≥400 gf, and a heat shrinkage temperature ≥180℃; the elastic buffer layer has a thickness of 0.5-1 mm; the cylindrical shell is made of high-strength cold-rolled steel of HV180 or higher, with a wall thickness of 0.30-0.35 mm for 18650 and 0.35-0.40 mm for 21700, and the explosion-proof valve has an opening pressure of 0.8-1.2 MPa.

[0020] Preferably, after in-situ polymerization and solidification, the semi-solid electrolyte forms an integrated solid-solid interface with the electrode and separator, which significantly improves the structural integrity and safety stability of the battery under needle penetration and heavy object impact.

[0021] In summary, the high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery and its preparation method of the present invention have the following advantages compared with traditional technologies: 1. The present invention uses a multi-layer composite current collector combined with an alumina transition interlayer, which can directionally induce microcracks and melt them during needle punching and impact, instantly cutting off the short circuit current and suppressing the expansion of internal short circuit from the source. 2. A high proportion of boehmite-coated LLZO solid-liquid composite semi-solid electrolyte is used, with non-flammable solid electrolyte as the main phase. Combined with in-situ solidification to form a dense interface, it has multiple functions such as flame retardancy, compression resistance, and lithium dendrite barrier. 3. All-pole ear flattening structure combination The current collector protrusion and the central elastic buffer layer form a dual stress absorption in the radial and axial directions, which significantly reduces the risk of damage to the lower electrode and diaphragm due to mechanical abuse. 4. The overall design of the collaborative safety system, unlike single safety improvements, enables ternary cylindrical batteries to stably pass heavy object impact and nail penetration safety tests while maintaining an energy density of 280-300Wh / kg, without fire, explosion, or smoke. 5. The solution is compatible with existing 18650 / 21700 cylindrical battery mass production lines, with low modification costs and good industrialization prospects.

[0022] The technical method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a structural diagram of a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to this application; Figure 2 This is a structural diagram of the PET-aluminum multilayer composite current collector of this application; Figure 3 This is a flowchart illustrating the preparation method of a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to this application.

[0024] Figure Labels 1. Cylindrical shell; 11. Shell bottom sealing structure; 2. Core; 21. Positive electrode sheet; 211. Aluminum layer; 212. PET layer; 213. Alumina transition interlayer; 22. Negative electrode sheet; 23. Diaphragm; 3. Electrolyte; 4. Cover plate assembly; 41. Shell end copper pressure sealing structure; 42. Cover plate layer; 43. Top insulating sealing gasket; 44. Cover plate current collector; 5. Center pin; 6. Modified silicone rubber elastic buffer; 7. Thermoelectric separation bidirectional explosion-proof valve. Detailed Implementation

[0025] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0026] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0027] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0028] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0029] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0030] This application provides a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery and its preparation method. Through the integrated and synergistic design of composite current collector, solid-liquid composite semi-solid electrolyte, full-tab buffer structure, central elastic buffer layer, high-safety separator and thermoelectric separation explosion-proof valve, internal short circuit is blocked from the source and thermal runaway is suppressed, so that the battery can successfully pass the mechanical abuse safety test.

[0031] On the one hand, this application proposes a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery, such as... Figure 1 As shown, it includes a cylindrical shell 1, a core 2, an electrolyte 3, a cover plate assembly 4, and a center pin 5; The cover plate assembly 4 is set above the cylindrical shell 1. The bottom of the cylindrical shell 1 is provided with a shell sealing and forming structure 11. The cylindrical shell 1 is made of high-strength cold-rolled steel of HV180 or above. The wall thickness of 18650 is 0.30-0.35mm, and the wall thickness of 21700 is 0.35-0.40mm. The opening pressure of the explosion-proof valve is 0.8-1.2MPa.

[0032] The center pin 5 is located in the center of the cylindrical housing 1, and its upper and lower ends are connected to the cover plate assembly 4 and the housing bottom sealing structure 11, respectively. The cover plate assembly 4 integrates a thermoelectric separation bidirectional explosion-proof valve 7, and from top to bottom includes a housing closing copper pressure sealing structure 41, a cover plate layer 42, a top insulating sealing gasket 43, and a cover plate manifold 44. The cover plate manifold 44 is provided with Type of buffer protrusion.

[0033] The two tab areas of the full tab flattening structure are laser welded to the bottom of the shell and the cover plate current collector 44. The cover plate current collector 44 and the modified silicone rubber elastic buffer 6 layers together form a radial and axial dual stress absorption structure.

[0034] The core 2 is wound around the outer ring of the center pin 5. The core 2 has a flattened structure with full tabs. A modified silicone rubber elastic buffer layer 6 is provided between the center hole of the core 2 and the center pin 5. The modified silicone rubber elastic buffer layer 6 has a thickness of 0.5-1mm. The center pin 5 has a hollow heat insulation structure.

[0035] The core 2 is composed of a sandwich-style spiral winding of a positive electrode 21, a separator 23, and a negative electrode 22; The positive electrode 21 uses a PET-aluminum multilayer composite current collector, the negative electrode 22 uses a copper-based polymer composite current collector, and the separator 23 uses a high-puncture double-sided ceramic-coated wet three-layer composite separator with a total thickness of 22-28μm, a puncture strength ≥400gf, and a heat shrinkage temperature ≥180℃.

[0036] like Figure 2 As shown, the PET-aluminum multilayer composite current collector has a thickness of 12-18μm, with a PET layer 212 in the middle and aluminum layers 211 on both sides. The thickness of the PET layer 212 is 4-8μm, and the thickness of the aluminum layer 211 is 3-6μm. An alumina transition interlayer 213 is provided between the aluminum layer 211 and the PET layer 212, which is used to induce microcracks and melt them under mechanical extrusion, so as to realize the self-cutting of short-circuit current.

[0037] Electrolyte 3 is filled in cylindrical shell 1. Electrolyte 3 is a solid-liquid composite semi-solid electrolyte with boehmite nano-coated LLZO, and is solidified by in-situ polymerization to form a continuous electrolyte phase. Electrolyte 3 is a solid-liquid composite semi-solid electrolyte, including LLZO solid electrolyte, boehmite coating layer, and liquid electrolyte. The particle size of LLZO solid electrolyte is 200-500nm, the thickness of boehmite coating layer is 5-15nm, the mass ratio of solid electrolyte is 90wt%-95wt%, and the liquid electrolyte is a fluoroethylene carbonate system with a proportion of 5wt%-10wt%. After in-situ polymerization at 60-70℃, the electrolyte forms a dense semi-solid interface, which has the ability to resist extrusion, block lithium dendrites and inhibit heat spread.

[0038] On the other hand, this application proposes a method for preparing a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery, such as... Figure 3 As shown, it includes the following steps: S1. The ternary cathode material, PVDF-HFP binder and compound conductive agent are made into a slurry and coated on the PET-aluminum composite current collector. The negative electrode slurry is coated on the copper-based polymer composite current collector. The slurry is dried, rolled and cut to control the edge burrs of the electrode sheet to ≤1μm. S2. The positive electrode 21, negative electrode 22 and separator 23 are wound into shape, and the winding tension tolerance is controlled to ±5%. The two sides of the core 2 are flattened by full-pole tabs. S3. Inject modified silicone rubber liquid into the center hole of core 2, insert hollow heat insulation center needle 5 and cure to form an elastic buffer layer; S4. Insert the core 2 into the housing and complete the laser welding encapsulation; S5. Vacuum injection of solid-liquid composite semi-solid electrolyte at 45℃ and -0.08MPa, followed by immersion for 2-3 hours, and then heating to 60-70℃ for in-situ polymerization and curing. S6. The finished battery is obtained through formation and capacity testing.

[0039] The PET-aluminum multilayer composite current collector, electrolyte 3, modified silicone rubber elastic buffer layer 6, full-tab flattening structure, high-puncture double-sided ceramic coated wet three-layer composite diaphragm and thermoelectric separation bidirectional explosion-proof valve 7 form a synergistic safety system, which can simultaneously achieve rapid short-circuit current cut-off, thermal runaway path blocking and mechanical stress buffering under needle puncture and heavy object impact.

[0040] Furthermore, the diaphragm 23 has a total thickness of 22-28μm, a puncture strength ≥400gf, and a heat shrinkage temperature ≥180℃; the elastic buffer layer has a thickness of 0.5-1mm; the cylindrical shell 1 is made of high-strength cold-rolled steel of HV180 or higher, with a wall thickness of 0.30-0.35mm for 18650 and 0.35-0.40mm for 21700, and the explosion-proof valve has an opening pressure of 0.8-1.2MPa.

[0041] After in-situ polymerization and solidification, the semi-solid electrolyte forms an integrated solid-solid interface with the electrode and separator 23, which significantly improves the structural integrity and safety stability of the battery under needle penetration and heavy object impact.

[0042] Example 1 A type 18650 high-safety ternary cylindrical lithium-ion battery, wherein the cylindrical casing 1 is a high-strength cold-rolled steel casing; The positive electrode 21 uses NCM622 ternary material as the active material, combined with PVDF-HFP composite binder and carbon nanotube-graphene composite conductive agent. The positive current collector of the positive electrode 21 uses a 15μm PET-aluminum multilayer composite current collector, with the thickness of the middle PET layer 212 being 6μm, the thickness of the aluminum layers 211 on both sides being 4.5μm each, and an alumina transition interlayer 213 in the middle. The negative electrode 22 uses an artificial graphite negative electrode, and the negative electrode current collector uses a 10μm copper-based polypropylene composite current collector; Membrane 23 is a 25μm double-sided alumina ceramic coated PP / PE / PP wet process membrane; Electrolyte 3 is a 92% boehmite-coated LLZO solid electrolyte and an 8% fluoroethylene carbonate-based liquid electrolyte, with added epoxy-based in-situ polymerized monomers; The core 2 has a flattened structure with all tabs, a 0.8mm modified silicone rubber buffer layer in the center, and the center pin 5 has a hollow heat insulation structure. The shell wall thickness is 0.32mm, and the cover plate is equipped with a thermoelectric separation bidirectional explosion-proof valve.

[0043] Preparation method: (1) NCM622, PVDF-HFP and carbon nanotube-graphene were prepared into a positive electrode slurry with a solid content of 72% in a ratio of 96:2:2. The slurry was coated on the composite current collector, dried and rolled at 900 N / mm. After slitting, the electrode burrs were ≤1 μm. (2) Prepare a negative electrode slurry with a solid content of 68% by mixing artificial graphite, water-based binder and conductive carbon black in a ratio of 95:3:2, coat it on a copper-based composite current collector, and roll it with 700N / mm. (3) Wind the electrode sheet and diaphragm 23, control the tension tolerance ±4%, flatten the two side tabs, inject buffer adhesive and insert the center needle 5 to cure; (4) Install the 18650 housing, laser weld the tabs to the housing and cover plate, welding power 400W; (5) Inject semi-solid electrolyte under vacuum at 45℃, soak for 2.5h, and solidify in situ at 65℃; (6) Formation at 45℃ with low current, and then capacity testing to obtain the finished battery.

[0044] Comparative Example 1 A conventional 18650 ternary cylindrical battery was prepared using a traditional pure aluminum current collector, pure liquid electrolyte, and single or double tab structure, with the remaining materials and parameters being the same as in Example 1.

[0045] Performance testing: Safety and electrochemical performance tests were conducted on the batteries of Example 1 and Comparative Example 1. The test standards were: UN38.3 heavy object impact (9.1kg hammer, 61cm drop) and UL1642 needle penetration (3mm steel needle, full speed penetration). The results are shown in Table 1.

[0046] Table 1 Performance Test Comparison Results

[0047] Test results show that the ternary cylindrical battery prepared by this invention can successfully pass the heavy object impact and nail penetration safety tests, while maintaining excellent energy density and cycle performance, thus solving the technical problem of the non-compliance of safety performance of traditional ternary cylindrical batteries.

[0048] Example 2 A 21700 type high-safety ternary cylindrical lithium-ion battery has a casing wall thickness of 0.38mm, a positive electrode made of NCM811 ternary material, and a solid electrolyte mass ratio of 94%. The remaining structure and preparation process are the same as in Example 1. The prepared battery has a full-charge state needle penetration temperature rise of ≤30℃, no abnormalities under heavy object impact, and an energy density of 305Wh / kg. It has passed all safety tests.

[0049] In summary, this invention constructs a collaborative safety system from six aspects: self-cutting composite current collector, flame-retardant and heat-insulating semi-solid electrolyte, central buffer energy absorption, low stress of all tabs, high-safety separator, and directional explosion-proof pressure relief. It overcomes the technical difficulties of ternary 18650 / 21700 cylindrical batteries failing heavy object impact and nail penetration tests, and has both high safety and high energy density characteristics. It is suitable for the transformation of existing mass production lines and has extremely high industrialization value.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical methods of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical methods to deviate from the spirit and scope of the technical methods of the present invention.

Claims

1. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery, comprising a cylindrical shell, a core, an electrolyte, a cover assembly, and a center pin, characterized in that: The cover plate assembly is disposed above the cylindrical shell, and the bottom of the cylindrical shell is provided with a shell sealing and forming structure; The central pin is located in the center of the cylindrical shell, and its upper and lower ends are respectively connected to the cover plate assembly and the shell bottom sealing structure. The core is wound around the outer ring of the central needle; The core is composed of a sandwich-style spiral winding of a positive electrode sheet, a separator, and a negative electrode sheet; The positive electrode uses a PET-aluminum multilayer composite current collector, and the negative electrode uses a copper-based polymer composite current collector. The electrolyte is filled in a cylindrical shell.

2. The high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 1, characterized in that, The core has a full-tie flattening structure; A modified silicone rubber elastic buffer layer is provided between the center hole and the center pin of the core. The central needle has a hollow, heat-insulating structure.

3. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 2, characterized in that, The electrolyte is a solid-liquid composite semi-solid electrolyte with boehmite nano-coated LLZO, and is formed by in-situ polymerization and solidification to form a continuous electrolyte phase. The diaphragm is a high-penetration double-sided ceramic-coated wet three-layer composite diaphragm.

4. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 1, characterized in that, The PET-aluminum multilayer composite current collector has a thickness of 12-18μm, with a PET layer in the middle and aluminum layers on both sides; The PET layer has a thickness of 4-8 μm, and the aluminum layer has a thickness of 3-6 μm; An alumina transition interlayer is provided between the aluminum layer and the PET layer to induce microcracks and melt them under mechanical extrusion, thereby achieving self-cutting of short-circuit current.

5. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 1, characterized in that, The electrolyte is a solid-liquid composite semi-solid electrolyte, comprising LLZO solid electrolyte, boehmite coating layer, and liquid electrolyte; Among them, the particle size of LLZO solid electrolyte is 200-500 nm; Boehmite coating thickness 5-15 nm; Solid electrolyte content: 90wt%-95wt%; The liquid electrolyte is a fluoroethylene carbonate system, accounting for 5wt%-10wt%; After the electrolyte is polymerized in situ at 60-70℃, a dense semi-solid interface is formed, which has the ability to resist extrusion, block lithium dendrites and inhibit heat spread.

6. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 1, characterized in that, The cover plate assembly integrates a thermoelectric separation bidirectional explosion-proof valve, which, from top to bottom, includes a housing constriction copper pressure sealing structure, a cover plate layer, a top insulating sealing gasket, and a cover plate manifold. The cover plate collector plate is equipped with Type of buffer protrusion.

7. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 1, characterized in that, The two tab areas of the full tab flattening structure are laser-welded to the bottom of the shell and the current collector plate of the cover plate. The cover plate current collector and the modified silicone rubber elastic buffer layer together form a radial and axial dual stress absorption structure.

8. A high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 1, characterized in that, The diaphragm has a total thickness of 22-28 μm, a puncture strength of ≥400 gf, and a heat shrinkage temperature of ≥180℃. The modified silicone rubber elastic buffer layer has a thickness of 0.5-1 mm; The cylindrical shell is made of high-strength cold-rolled steel of HV180 or above, with a wall thickness of 0.30-0.35mm for 18650 and 0.35-0.40mm for 21700. The explosion-proof valve has an opening pressure of 0.8-1.2MPa.

9. A method for preparing a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery, used to achieve the preparation of the high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The ternary cathode material, PVDF-HFP binder and compound conductive agent are made into a slurry and coated on the PET-aluminum composite current collector. The negative electrode slurry is coated on the copper-based polymer composite current collector. The slurry is dried, rolled and cut to control the edge burrs of the electrode sheet to ≤1μm. S2. Wind the positive electrode, negative electrode and separator into shape, control the winding tension tolerance ±5%, and flatten the full tabs on both sides of the core. S3. Inject modified silicone rubber liquid into the center hole of the core, insert the hollow heat insulation center needle and cure to form an elastic buffer layer; S4. Insert the core into the housing and complete the laser welding encapsulation; S5. Vacuum injection of solid-liquid composite semi-solid electrolyte at 45℃ and -0.08MPa, followed by immersion for 2-3 hours, and then heating to 60-70℃ for in-situ polymerization and curing. S6. The finished battery is obtained through formation and capacity testing.

10. The method for preparing a high-safety, thermal runaway-resistant ternary cylindrical lithium-ion battery according to claim 9, characterized in that, The PET-aluminum multilayer composite current collector, electrolyte, modified silicone rubber elastic buffer layer, full-tab flattening structure, high-puncture double-sided ceramic coated wet three-layer composite diaphragm, and thermoelectric separation bidirectional explosion-proof valve form a synergistic safety system, which simultaneously achieves rapid short-circuit current cutoff, thermal runaway path blocking, and mechanical stress buffering under needle penetration and heavy object impact.

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