A cylindrical battery shell and cylindrical battery
By using a fixed connection design between the outer and inner shells and an integrated insulation structure, the problems of complicated processes and insulation failure in the production of large cylindrical lithium-ion batteries are solved, resulting in reduced costs, improved insulation reliability and enhanced safety, making it suitable for mass production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANTAI LIHUA ELECTRIC POWER TECHNOLOGY CO LTD
- Filing Date
- 2026-06-08
- Publication Date
- 2026-07-31
AI Technical Summary
Existing cylindrical lithium-ion battery casing structures suffer from problems such as cumbersome processes, insulation failure, high production costs, and significant safety hazards. In particular, traditional split structures and inner wall sprayed insulation layer solutions have drawbacks such as membrane damage and peeling, high risk of infringement, and high production costs.
The outer shell and inner shell are designed with fixed connection. The outer shell is made of metal and the inner shell is made of insulating material. Multiple axial flow guide grooves and confluence grooves are set on the inner wall of the inner shell. They are integrated by thermal bonding or injection molding inserts. The inner shell is made of modified PP or PE as the base material with ceramic flame retardant filler to form an integrated insulating structure.
It simplifies production processes, reduces costs, improves insulation reliability and safety, enhances current conduction efficiency, adapts to large-scale mass production, and strengthens battery rate performance and cycle life.
Smart Images
Figure CN122494944A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery manufacturing technology, specifically to a cylindrical battery casing and a cylindrical battery. Background Technology
[0003] Currently, large cylindrical lithium-ion batteries (represented by 4680 and 4695 specifications) have become one of the mainstream technologies in the fields of new energy vehicles and energy storage due to their advantages such as high energy density, high rate performance, and low cost potential. However, the existing casing structure generally adopts the traditional split structure and the technical solution of spraying an insulating layer on the inner wall, which has many technical defects, as follows: The drawbacks of the traditional split structure (metal casing + independent film): Existing large cylindrical batteries generally adopt a split design of "metal casing + core with Mylar insulating film". This solution is complicated and the film is prone to damage and wrinkles during the core film application process. The film surface is easily scratched when the core is inserted into the casing, which can lead to insulation failure and cause a short circuit between the casing and the core. At the same time, the film application process requires additional investment in special equipment, labor and film materials. The cost of film application per cell is about 0.8-1.2 yuan. Moreover, it is difficult to automate production, which seriously affects mass production efficiency and product yield.
[0004] Limitations of the inner wall spraying insulation layer solution: Some companies have tried to achieve insulation by spraying ceramic or insulating coatings on the inner wall of the metal shell, but this approach has two major problems: First, the coating has poor adhesion to the metal shell, and it is prone to peeling and cracking after long-term contact with electrolyte, resulting in insufficient insulation reliability and safety hazards; Second, this technical approach has a dense patent portfolio (such as CATL and Guoxuan High-Tech's related spraying process and structure patents), which poses a very high risk of infringement. Moreover, the spraying process has high environmental protection requirements and high production costs, making it unsuitable for large-scale mass production. Summary of the Invention
[0006] To address the technical problems of high production costs and insulation failure during production in existing technologies, this invention provides a cylindrical battery casing and a cylindrical battery, which reduces costs and increases efficiency, improves current conduction efficiency, ensures reliable insulation, and enhances safety.
[0007] This invention provides a cylindrical battery casing, comprising an outer casing and an inner casing fixedly connected. The outer casing is made of a metal material, and the inner casing is made of an insulating material. The inner wall of the inner casing has multiple guide grooves arranged along the axial direction of the inner casing. The bottom of the inner casing is provided with a converging groove, which includes a first converging groove and a second converging groove. The first converging groove is arranged in a ring, and the second converging groove is arranged axially and communicates with the guide grooves.
[0008] Furthermore, the outer shell and the inner shell are fixedly connected by thermal bonding; or, the outer shell and the inner shell are fixedly connected by injection molding inserts.
[0009] Furthermore, the inner shell uses modified PP or PE as the base material and adds ceramic flame-retardant filler.
[0010] Furthermore, the thickness of the inner shell is 0.15-0.5 mm.
[0011] Furthermore, the flow channels extend upward through the upper end of the inner shell and downward to the bottom of the inner shell. There are 6-12 flow channels, which are evenly distributed along the inner wall of the inner shell.
[0012] Furthermore, the cross-section of the guide channel is a circular arc groove or a trapezoidal groove, the width of the guide channel is 1.0-2.0mm, and the depth of the guide channel is 0.15-0.3mm.
[0013] Furthermore, the outer shell is made of nickel-plated steel or aluminum alloy with a thickness of 0.3-0.5mm.
[0014] Furthermore, the insulating layer between two adjacent guide channels forms insulating ribs.
[0015] Furthermore, a guide ramp is provided on the top of the inner shell.
[0016] A cylindrical battery includes the aforementioned outer casing, an inner casing containing a battery cell, and a top cover welded to the opening of the outer casing.
[0017] The beneficial effects of this invention are as follows: Cost reduction and efficiency improvement, process simplification: Eliminating the core-coating process saves on coating equipment, labor and film material costs, reducing the cost per cell by 0.8-1.2 yuan; reducing one production process improves the efficiency of automated production, reduces the defect rate caused by coating damage and scratches, and improves the overall battery yield by 2-5%, making it suitable for large-scale mass production.
[0018] Significantly improved flow efficiency: The combined design of axial flow channel and bottom confluence channel reduces electrolyte injection time by 30-50% (from the conventional 120s to 60-80s for 4680 specification). The electrolyte can quickly and evenly wet the electrode assembly, with no dead corners or dry areas, making it suitable for 6C and above fast charging scenarios, reducing concentration polarization, and improving battery rate performance and cycle life.
[0019] Reliable insulation and high safety: The insulating composite layer is integrated with the metal shell, eliminating the risk of detachment or cracking and completely preventing short circuits between the core and the metal shell; thermal runaway gas is directionally guided through the guide slope and axial guide groove to avoid lateral ablation and reduce the risk of heat spread; the groove ribs buffer the core expansion and prevent the shell from cracking due to compression, further improving battery safety.
[0020] Highly adaptable and consistent: The structural design is compatible with all 46-series large cylindrical batteries such as 4680, 4695, and 46100. Only the casing size, number and size of the current guide grooves need to be adjusted. The core is smoothly inserted into the casing without scratching the separator or jamming. It has high dimensional accuracy, good consistency during mass production, and is compatible with high-speed automated production lines. Attached Figure Description
[0022] 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, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention.
[0024] Explanation of main reference numerals: 1-outer shell, 2-inner shell, 3-guide channel, 41-first confluence channel, 42-second confluence channel, 5-insulating rib. Detailed Implementation
[0026] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.
[0027] like Figure 1 As shown, an embodiment of the present invention provides a cylindrical battery casing, including an outer casing 1 and an inner casing 2 fixedly connected. The outer casing 1 is made of metal material, and the inner casing 2 is made of insulating material. The inner wall of the inner casing 2 has multiple guide grooves 3 arranged along the axial direction of the inner casing 2. The bottom of the inner casing 2 is provided with a converging groove, which includes a first converging groove 41 and a second converging groove 42. The first converging groove 41 is arranged in a ring, and the second converging groove 42 is arranged axially and communicates with the guide grooves 3.
[0028] The outer shell 1 is made of nickel-plated steel or aluminum alloy, with a thickness of 0.3-0.5mm, preferably 0.4mm. It has a smooth cylindrical surface and no drainage grooves, scratches, or weakened structures on the inner wall. Only the shell opening retains conventional flanges and grooves for sealing and welding with the top cover. Its core function is to provide structural support, explosion-proof pressure resistance, and negative electrode current collection, ensuring the overall mechanical strength of the shell.
[0029] The inner shell 2 uses modified PP (polypropylene) or PE (polyethylene) as the base material, with added ceramic flame-retardant fillers (such as alumina and magnesium hydroxide), and a thickness of 0.15-0.5mm, preferably 0.3mm. It is integrated with the outer metal shell through thermal bonding or injection molding inserts, without gaps or bubbles, directly replacing the traditional core outer film without the need for additional film wrapping. Its core function is to achieve insulation isolation between the core and the metal shell, preventing shell-core short circuits, and at the same time, it serves as a carrier for the electrolyte guide channel 3, supporting the core and buffering core expansion displacement.
[0030] Axial electrolyte guide channels 3 are disposed on the inner wall of the inner shell 2. The inner wall of the metal shell is kept smooth. There are 6-12 channels, preferably 8, which are evenly distributed circumferentially along the inner wall of the insulation layer. The cross-section is a circular arc channel or a trapezoidal channel, preferably a circular arc channel. The channel width is 1.0-2.0 mm, preferably 1.5 mm, and the channel depth is 0.15-0.3 mm, preferably 0.2 mm. The guide channels 3 extend upward through the upper end of the inner shell 2 and downward to the bottom of the inner shell 2. The guide channels 3 guide the rapid flow of electrolyte to achieve uniform wetting of the electrode assembly. At the same time, they serve as a channel for the flow of thermal runaway gas. The bottom of all axial electrolyte guide channels 3 converges into a confluence channel to achieve centralized convergence of electrolyte, avoid dead zones of liquid accumulation at the bottom, accelerate the wetting of the bottom of the electrode assembly, and shorten the injection time.
[0031] The manifold is located at the bottom of the inner shell 2, including a first manifold 41 and a second manifold 42. The first manifold 41 is arranged in a ring, and the number of the first ring is one or more with the radius increasing sequentially and arranged concentrically. Multiple second manifolds 42 are arranged axially at the bottom of the inner shell 2, and the multiple second manifolds 42 are arranged in an array along the circumferential direction and are connected to the guide channel 3. The width of the first manifold 41 is 2.0-3.0mm, preferably 2.5mm, and the depth is 0.2-0.4mm, preferably 0.3mm. The combination design of the guide channel 3 and the bottom manifold reduces the electrolyte injection time by 30-50% (from the conventional 120s to 60-80s for 4680 specifications). The electrolyte can quickly and evenly wet the electrode assembly, with no dead corners or dry areas, which is suitable for 6C and above fast charging scenarios, reduces concentration polarization, and improves battery rate performance and cycle life.
[0032] The top of the inner shell 2 is provided with a guide slope. The inter-slot insulating ribs 5 are formed by the insulating layer between two adjacent axial guide grooves 3, with a width of 2.0-3.0 mm, preferably 2.5 mm. They contact the outer edge of the core and guide and position the core, preventing it from being eccentric or wobbling, while also preventing the core from being scratched when it enters the shell. Thermal runaway gas is directionally diverted through the guide slope and axial guide grooves 3, avoiding lateral ablation and reducing the risk of thermal propagation. The inter-slot ribs buffer the expansion of the core, preventing the shell from cracking due to compression of the metal shell, further improving battery safety.
[0033] Example 1 is a specific embodiment of the manufacturing steps of the casing of a cylindrical battery according to the present invention: S1. Metal shell pretreatment: Select 4680 specification nickel-plated steel shell, degrease and remove rust, use sandblasting process to slightly roughen the inner wall, control the roughness to Ra2.0, and dry it after treatment for later use.
[0034] S2. Prefabricated insulating cylinder: The modified PP + 10% alumina ceramic filler is heated and melted using an extrusion process, and then extruded into an insulating cylinder with 8 arc-shaped guide grooves on the inner wall, a confluence groove at the bottom, and a 20° guide slope at the top. The outer diameter of the insulating cylinder is 45.8mm (0.1mm smaller than the inner diameter of the metal shell) to ensure tight bonding in subsequent processes.
[0035] S3. Inserting the insulating cylinder: Slowly and steadily insert the prefabricated insulating cylinder into the metal shell, adjust its position to ensure that the insulating cylinder is aligned with the inner wall of the metal shell without any offset or wrinkles.
[0036] S4. Thermal Composite Shaping: The metal shell containing the insulating cylinder is placed in a heating furnace, and the heating temperature is controlled at 130℃. At the same time, an internal expansion fixture is used to perform internal expansion treatment on the insulating cylinder. The internal expansion pressure is 0.2MPa, and the temperature is maintained for 4 minutes to make the insulating cylinder and the inner wall of the metal shell fit tightly without gaps or air bubbles. Then, it is naturally cooled to room temperature to complete the composite molding.
[0037] S5. Post-processing: Special equipment is used to flanging and grooving the shell opening, trimming the burrs on the shell edge, and removing surface impurities; the finished product is tested for insulation resistance, dimensional accuracy, and bonding force. Once qualified, it is a 4680 specification composite shell finished product.
[0038] The difference between Embodiment 2 and Embodiment 1 is that the metal outer shell 1 and the insulating cylinder are integrally connected by injection molding inserts. By placing the prefabricated insert of the metal outer shell 1 into the mold for injection molding, an integrated product of the metal outer shell 1 and the inner shell 2 of the insulating cylinder is formed.
[0039] An embodiment of the present invention also provides a cylindrical battery, including the outer casing of the cylindrical battery described above, with a battery cell disposed inside the inner casing 2, and a top cover welded to the opening of the outer casing.
[0040] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.
Claims
1. A casing for a cylindrical battery, characterized in that, It includes an outer shell and an inner shell that are fixedly connected. The outer shell is made of metal and the inner shell is made of insulating material. The inner wall of the inner shell has multiple guide grooves arranged along the axial direction of the inner shell. The bottom of the inner shell is provided with a converging groove, which includes a first converging groove and a second converging groove. The first converging groove is arranged in a ring and the second converging groove is arranged axially and is connected to the guide groove.
2. The casing of a cylindrical battery as described in claim 1, characterized in that, The outer shell and the inner shell are fixedly connected by thermal bonding; or, the outer shell and the inner shell are fixedly connected by injection molding inserts.
3. The casing of a cylindrical battery as described in claim 1, characterized in that, The inner shell is made of modified PP or PE as the base material, with added ceramic flame-retardant filler.
4. The casing of a cylindrical battery as described in claim 3, characterized in that, The thickness of the inner shell is 0.15-0.5mm.
5. The casing of a cylindrical battery as described in claim 1, characterized in that, The flow channels extend upward through the upper end of the inner shell and downward to the bottom of the inner shell. There are 6-12 flow channels, which are evenly distributed along the inner wall of the inner shell.
6. The casing of a cylindrical battery as described in claim 1, characterized in that, The cross-section of the guide channel is a circular arc groove or a trapezoidal groove. The width of the guide channel is 1.0-2.0mm and the depth of the guide channel is 0.15-0.3mm.
7. The casing of a cylindrical battery as described in claim 1, characterized in that, The outer shell is made of nickel-plated steel or aluminum alloy with a thickness of 0.3-0.5mm.
8. The casing of a cylindrical battery as described in claim 1, characterized in that, The insulating layer between two adjacent flow channels forms an insulating rib.
9. The casing of a cylindrical battery as described in claim 1, characterized in that, The top of the inner shell is provided with a guide ramp.
10. A cylindrical battery, characterized in that, The casing includes a cylindrical battery as described in any one of claims 1-9, wherein a battery cell is disposed inside the inner casing, and a top cover is welded to the opening of the casing.