Puncture-resistant and explosion-proof cylindrical lithium battery
By using an insulating sleeve to isolate the steel shell from the negative electrode in the lithium battery, setting up vertical positive and negative electrode tabs, and replacing the PE film with a PPS film, the problem of short circuit and explosion caused by puncture in traditional lithium batteries is solved, achieving puncture resistance and explosion prevention.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-27
- Publication Date
- 2026-03-10
AI Technical Summary
Traditional 18650 cylindrical lithium batteries are prone to electrical short circuits when punctured, leading to high-temperature ignition and deflagration. Existing technologies cannot achieve the goal of preventing combustion and explosion.
An insulating sleeve is used to isolate the steel shell from the negative electrode. The positive and negative electrode tabs are set vertically and isolated with insulating tape. A high-temperature stable PPS membrane is used instead of a PE diaphragm to ensure that the positive and negative electrodes do not come into direct contact.
It effectively avoids short circuits between the steel shell and the positive electrode tab, reduces the probability of the tab being punctured, reduces the risk of short circuits, prevents the expansion of local short circuits, and improves the safety of lithium batteries.
Smart Images
Figure CN121642331A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery technology, and in particular to a puncture-resistant and explosion-proof cylindrical lithium battery. Background Technology
[0002] 18650 cylindrical lithium batteries are among the most widely used cylindrical batteries, extensively used in power banks, power tools, instruments, and other devices. However, traditional 18650 cylindrical lithium batteries have serious safety hazards: their steel casing is directly connected to the negative electrode; if a conductive object pierces it, it can easily cause the steel casing to contact the positive electrode tab, creating an electrical short circuit, instantly generating high temperatures and igniting the internal metal oxides. Simultaneously, the PE separator used in traditional lithium batteries has porous characteristics and strong thermal shrinkage, allowing oxygen atoms to easily penetrate, leading to widespread short circuits between the positive and negative electrodes, and subsequently triggering a chain reaction of explosion and combustion. While manufacturers have attempted to improve lithium battery safety, they have yet to achieve the goal of preventing lithium batteries from burning or exploding under puncture tests. Summary of the Invention
[0003] The purpose of this invention is to provide a puncture-resistant and explosion-proof cylindrical lithium battery, solving the problem that traditional 18650 cylindrical lithium batteries are prone to short circuits and explosions when punctured.
[0004] To achieve the above objectives, the present invention provides the following technical solution: A puncture-resistant and explosion-proof cylindrical lithium battery includes a steel casing, a battery cell, a composite separator, and an insulating sleeve. The battery cell is formed by winding a positive electrode film, a negative electrode film, and a composite separator. A positive electrode tab is welded to the aluminum foil current collector of the positive electrode film, and a negative electrode tab is welded to the copper foil current collector of the negative electrode film. The planes of the positive and negative electrode tabs are perpendicular to each other and far from the center of the battery cell. The composite separator is a composite film of PPS film and PE film with a thickness of 15-20μm. The insulating sleeve inside the steel casing isolates the steel casing body from the negative electrode. The conductive sheets of both the positive and negative electrode tabs are covered with insulating tape. The positive electrode post at the top of the steel casing is electrically connected to the positive electrode tab, and the negative electrode tab has no direct electrical contact with the steel casing.
[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The insulating sleeve ensures that the steel shell body has no electrical connection with the negative electrode. When a foreign object punctures the steel shell, the outer shell no longer acts as an electrode to participate in the short circuit, thus structurally preventing the steel shell from directly short-circuiting with the positive electrode tab. 2. The positive and negative tabs are perpendicular to each other and far from the center of the battery cell, which greatly reduces the probability of a conductive object puncturing both tabs at the same time; the insulating tape on the tabs further reduces the risk of short circuits, and even if a conductive object comes into contact with the tabs, it can easily slide away, eliminating the possibility of electrical short circuits between the positive and negative tabs; 3. Composite separators replace traditional PE separators. PPS has strong high-temperature stability and can prevent indirect short circuits between positive and negative current collectors caused by puncture. Even if a local short circuit occurs, it can avoid the rapid shrinkage of the PE separator, which would lead to an expansion of the short circuit area and improve the safety performance of lithium batteries. Attached Figure Description
[0006] Figure 1 Schematic diagram of a traditional cylindrical lithium battery structure; Figure 1 In the diagram, 1 is the positive electrode, 2 is the diaphragm, 3 is the negative electrode, 4 is the steel shell, and 5 is the positive electrode tab.
[0007] Figure 2 Schematic diagram of a traditional lithium battery puncture short circuit; Figure 2 In the middle, 6 is the negative electrode tab, which shows the structure of a traditional lithium battery where the positive electrode, separator, and negative electrode are wound and then put into a steel shell, with the positive electrode tab connected to the positive electrode post and the negative electrode tab directly connected to the steel shell. 7 is the steel needle, which shows the state where the steel shell and the positive electrode tab come into contact and form a short circuit after the steel needle is inserted.
[0008] Figure 3 : Schematic diagram of the positive electrode film and positive electrode tab structure of this invention; Figure 3 In the diagram, a represents the length of the positive electrode film, b represents the width of the positive electrode tab welding position, c represents the length of the positive electrode tab, 8 represents the positive electrode film, and 9 represents the positive electrode tab. This diagram illustrates the structure in which the positive electrode material is coated onto an aluminum foil current collector, and the positive electrode tab is welded to a suitable position on the current collector.
[0009] Figure 4 : Schematic diagram of the negative electrode film and negative electrode tab structure of this invention; Figure 4 In the diagram, h represents the length of the negative electrode film, c represents the length of the negative electrode tab, 10 represents the negative electrode film, and 11 represents the negative electrode tab. This diagram illustrates the structure in which the negative electrode material is coated onto a copper foil current collector, and the negative electrode tab is welded to a suitable position on the current collector.
[0010] Figure 5 : Schematic diagram of the composite diaphragm structure of the present invention; Figure 5 In the diagram, 12 represents a PPS membrane and 13 represents a PE membrane; this demonstrates a composite membrane structure formed by combining PPS and PE membranes with polyurethane adhesives.
[0011] Figure 6 : Schematic diagram of the winding end face of the battery cell of the present invention; Figure 6 In the diagram, 14 represents the battery casing, 15 represents the positive electrode tab, and 16 represents the negative electrode tab; the diagram shows the winding end face structure where the positive and negative electrodes are perpendicular to each other and far from the center of the battery cell.
[0012] Figure 7 : Schematic diagram of the overall structure of the lithium battery of this invention; Figure 7 In the diagram, 17 is the steel shell, 18 is the insulating sleeve, 19 is the positive electrode, 20 is the negative electrode, 9 is the positive electrode tab, and 11 is the negative electrode tab. This demonstrates the overall structure where the battery cell is installed in a steel shell with an insulating sleeve, the positive electrode tab is connected to the positive electrode post, and the negative electrode is isolated from the main body of the steel shell by the insulating sleeve. Detailed Implementation
[0013] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.
[0014] A puncture-resistant and explosion-proof 18650 cylindrical lithium battery, the specific structure of which is as follows: The positive electrode film 8 is made by coating a positive electrode material such as lithium cobalt oxide onto an aluminum foil current collector, and a nickel positive electrode tab 9 is welded to one end of the aluminum foil current collector; the negative electrode film 10 is made by coating a negative electrode material such as graphite onto a copper foil current collector, and a nickel negative electrode tab 11 is welded to one end of the copper foil current collector.
[0015] The composite diaphragm is made of an 18μm thick PPS membrane 12 and a 12μm thick PE membrane 13 bonded together with polyurethane adhesive, with a total thickness of 20μm; the PPS membrane 12 is made from polyphenylene sulfide powder containing ion channels through preforming and rolling.
[0016] Apply polyimide insulating tape to the conductive sheets of the positive and negative electrodes, and design the welding positions of the positive and negative electrodes so that they are perpendicular to each other after winding, and the distance from the center of the battery cell is not less than 5mm.
[0017] The positive electrode membrane 8, composite separator, and negative electrode membrane 10 are stacked and wound in sequence to form a battery cell. The insulating sleeve 18 is placed inside the bottom and side wall of the steel shell 17. The battery cell is then installed into the steel shell. The positive electrode tab 9 is welded to the positive electrode 19 on the top of the steel shell. The negative electrode tab 11 is suspended and has no direct contact with the steel shell 17.
[0018] Lithium hexafluorophosphate or an equivalent electrolyte is injected into the steel shell 17, and the opening of the steel shell is sealed by laser welding to complete the lithium battery preparation.
[0019] The lithium battery was subjected to a puncture test: a steel needle with a diameter of 3 mm was inserted into the center of the cell at a speed of 5 mm / s and held in place for 30 minutes. The lithium battery did not burn or explode, indicating that it has excellent puncture resistance and explosion protection performance.
[0020] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.
Claims
1. A cylindrical lithium battery resistant to puncture and explosion, comprising a steel can (17) and an electrode core, characterized in that, It also includes composite diaphragm (12), (13) and insulating sleeve (18); the electric core is wound by positive film (8), negative film (10) and the composite diaphragm, the positive film (8) is welded with positive lug (9), the negative film (10) is welded with negative lug (11), the positive lug (9) and the negative lug (11) are arranged in the perpendicular state, and they are all far from the electric core center position;The composite diaphragm is the film that PPS film (12) and PE film (13) are formed by polyamide glue compound, and the thickness is 15-20 μm;The insulating sleeve (18) is arranged in the steel shell (17) inside, so that the steel shell main body and negative pole are mutually insulated and are not electrically connected;The conductive sheet of the positive lug (9) and the negative lug (11) is all pasted with insulating tape.
2. The puncture-resistant, explosion-proof cylindrical lithium battery according to claim 1, characterized in that, The positive film (8) is made of positive material coated on aluminum foil current collector, and the negative film (10) is made of negative material coated on copper foil current collector.
3. The puncture-resistant, explosion-proof cylindrical lithium battery of claim 1, wherein, The PPS film (12) in the composite diaphragm is the polyphenylene sulfide powder containing ion channel generated by hydrothermal reaction, which is made into a film by blanking and rolling.
4. The puncture-resistant, explosion-proof cylindrical lithium battery of claim 1, wherein, The top of the steel shell (17) is provided with a positive electrode (19), and the positive electrode (19) is electrically connected with the positive lug (9). The bottom of the steel shell (17) is connected with the negative lug and the negative copper foil (20), and the negative lug (11) has no direct electrical contact with the main body of the steel shell (17).