Method of processing a hybrid safety battery
By using separators of different materials stacked together and a through-link structure in the battery, the problem of insufficient low-temperature performance and safety of lithium iron phosphate batteries has been solved, and normal charging and discharging and improved safety of the battery in low-temperature environments have been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HENAN MECHANICAL & ELECTRICAL ENG COLLEGE
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-19
AI Technical Summary
In the existing technology, lithium iron phosphate batteries have poor charge and discharge capabilities and insufficient safety in low-temperature environments, while ternary lithium batteries have good charge and discharge capabilities but poor safety in low-temperature environments. There are still safety hazards when they are used together.
Two different materials of separator are stacked or combined to form a hybrid separator, and the electrode is stacked layer by layer through the hybrid separator. Combined with the through-link structure, the second separator with high melting point and high porosity is used to improve safety, and the second positive electrode with excellent low temperature performance is heated at low temperature to improve charge and discharge efficiency.
The battery was able to charge and discharge normally in low-temperature environments, which improved the battery's safety and structural stability, broadened its application range, reduced costs, and maintained its electrical performance.
Smart Images
Figure CN122246278A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery assembly technology, specifically a processing method for a hybrid safety battery. Background Technology
[0002] Lithium iron phosphate batteries have relatively high safety, but their charge and discharge capabilities are poor at low temperatures; while ternary lithium batteries have good charge and discharge capabilities at low temperatures, but their safety is poor. Currently, lithium iron phosphate and ternary lithium batteries are often mixed to give the batteries good low-temperature performance, but safety risks still exist. Summary of the Invention
[0003] To address the problems in the prior art, this invention provides a processing method for a hybrid safety battery, aiming to improve the battery's low-temperature performance while enhancing its safety.
[0004] A method for manufacturing a hybrid safety battery includes the following steps: Step 1: Combine a first diaphragm of a first material and a second diaphragm of a second material by overlapping and winding them together to form a hybrid diaphragm; wherein the melting point, insulation performance and hardness of the second diaphragm are all greater than those of the first diaphragm; Step 2: The first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode are stacked layer by layer using a hybrid separator, and the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode are alternately stacked to form a battery cell; wherein, the first positive electrode is made of lithium iron phosphate, and the second positive electrode is made of at least one of the following materials with better low-temperature performance than the first positive electrode: ternary material, lithium cobalt oxide, lithium manganese oxide, sodium iron sulfate, or sodium vanadium phosphate; the second positive electrode heats up before the first positive electrode in a low-temperature environment to heat the first positive electrode and improve its low-temperature charge and discharge efficiency; Step 3: Extend the tabs of the first positive electrode and the second positive electrode from the battery cell and stack them together to form a positive electrode tab; Step 4: Extend the tabs of the first negative electrode and the second negative electrode from the battery cell and stack them together to form a negative electrode tab; Step 5: Place the battery cell into the aluminum-plastic film casing, seal the top and sides, and leave a liquid injection port; Step 6: Inject electrolyte into the drying chamber to form a battery.
[0005] Furthermore, both the first and second negative electrode sheets are made of carbon; the second positive electrode sheet is made of ternary material.
[0006] Furthermore, the first diaphragm is made of polyethylene or polypropylene, and the second diaphragm includes polytetrafluoroethylene, soluble polytetrafluoroethylene, or fluorinated ethylene propylene copolymer.
[0007] Furthermore, the porosity of the first diaphragm is greater than 44%, and the porosity of the second diaphragm is greater than 85%.
[0008] Furthermore, the second diaphragm is a microporous film made by calendering, extrusion or biaxial stretching.
[0009] Furthermore, the mixing membrane is provided between the first positive electrode and the first negative electrode and the second negative electrode on both sides, and the mixing membrane is provided between the second positive electrode and the first negative electrode and the second negative electrode on both sides.
[0010] Furthermore, a through hole is pre-drilled in the middle of the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode, and the through holes of the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode correspond to each other; The first and second diaphragms are heat-fused at the corresponding through-hole positions to form a clearance hole; The through hole and the clearance hole are interconnected, thus forming a clearance channel; A connecting rod is pre-installed through the clearance channel, and after the battery cell is packaged in the casing, the two ends of the connecting rod are laser-welded to the two side walls of the metal casing.
[0011] Furthermore, an insulating gap or insulating material is provided between the outer wall of the connecting rod and the inner wall of the clearance channel.
[0012] Further, it can be made by laminating mixed diaphragms, or by using a composite process / intermittent composite process.
[0013] A hybrid safety battery comprising a battery manufactured by the method described above.
[0014] The beneficial effects of this invention are as follows: This invention combines or integrates two different materials of separator to form a double-layer safety protection. One layer, due to its material properties, exhibits high temperature resistance and high flame retardancy, enhancing battery safety and truly making the battery safer, achieving genuine flame retardancy and battery safety. Then, the first negative electrode, first positive electrode, second negative electrode, and second positive electrode are stacked layer by layer using the mixed separator to form the battery cell module required by the process. The characteristic of this battery is that, in a lithium iron phosphate battery, it includes n*1 positive electrode sheets with superior low-temperature performance. Its function is to enable the battery to operate and charge / discharge normally at low temperatures of -5±5℃, eliminating the need for separate heating elements or constant temperature chambers, reducing battery costs, and broadening its application range. The insulation, melting point, and hardness of the second separator are greater than those of the first separator, and their combined use fully utilizes the advantages of the mechanical and physical properties of each layer of material. The positive and negative electrode tabs are stacked separately, packaged in a casing, and then connected via a busbar. This invention improves the charge and discharge efficiency of lithium iron phosphate battery positive electrode by using interlaced low-temperature positive electrode sheets to raise the temperature at low temperatures. At the same time, it enhances safety performance by using a second separator with a high melting point and high porosity. Furthermore, it provides a through-link in the middle of the electrode sheet to suppress bulging of the casing, which can better solve the safety performance problem of metal-cased batteries. This results in a hybrid safety battery with a wide temperature range and high safety.
[0015] This invention improves the charging and discharging efficiency of the first positive electrode by generating a temperature rise in the second positive electrode under low temperature conditions, and at the same time improves the safety performance by using a second separator with a high melting point and high porosity, thereby producing a safe low-temperature lithium-ion battery with a wide temperature range and high safety performance. In this invention, the first positive electrode is heated by first heating the second positive electrode under low temperature conditions, thereby improving the charging and discharging efficiency of the first positive electrode. During normal operation, the second separator provides dual protection and supports the first separator, preventing wrinkles and damage. Thus, through the combination and complementarity of various performance materials, the battery of this invention can adapt to a wider temperature range and has better safety. Attached Figure Description
[0016] Figure 1 This is a cross-sectional view of the hybrid safety battery in this invention. Figure 2 This is a schematic diagram showing the internal structure of the hybrid safety battery in this invention. Figure 3 This is a schematic cross-sectional view of the hybrid safety battery in this invention. Detailed Implementation
[0017] The present invention will now be described in detail with reference to the accompanying drawings. Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The directional terms such as left, center, right, top, and bottom in the embodiments of the present invention are only relative concepts or referenced to the normal use state of the product, and should not be considered restrictive.
[0018] First embodiment: A method for manufacturing a hybrid safety battery, such as Figure 1 , Figure 2 and Figure 3 As shown, it includes the following steps: Step 1: Combine the first diaphragm of the first material and the second diaphragm of the second material by overlapping and winding to form a hybrid diaphragm 3; The first diaphragm is made of polyethylene (PE) material, with a thickness of 16 μm, a porosity of 45%, and a melting point of 120°C; the second diaphragm is made of polytetrafluoroethylene (PTFE) microporous membrane, with a thickness of 12 μm, a porosity of 88%, a melting point of 327°C, a thermal decomposition temperature of 420°C, and an ignition point of approximately 670°C; in other embodiments, the two diaphragms can also be hot-pressed together through an intermittent composite process to form an integrated hybrid diaphragm 3, ensuring that the two layers of diaphragms do not slip relative to each other during subsequent winding. Step 2: Cut the first negative electrode 4, the first positive electrode 5, the second negative electrode and the second positive electrode 6 into the required sizes, and wind them sequentially through the mixing separator 3 so that the four types of electrodes are alternately stacked (the number of electrodes is configured according to different needs) to form the battery cell 2 (i.e., the battery cell). The first positive electrode 5 is made of lithium iron phosphate (LFP) and has a thickness of 120μm; The second positive electrode 6 is made of ternary material (NCM811) and has a thickness of 120μm; The low-temperature performance of the second positive electrode is greater than that of the first positive electrode of lithium iron phosphate. The low-temperature performance includes the charge and discharge efficiency under low-temperature conditions. The first negative electrode 4 and the second negative electrode are both made of negative electrode carbon material with a thickness of 100μm; In the stacked structure, a mixing membrane 3 is provided between each positive electrode and the negative electrode on both sides. That is, a mixing membrane 3 is provided between the first positive electrode 5 and the first negative electrode 4 and the second negative electrode on both sides; a mixing membrane 3 is also provided between the second positive electrode 6 and the first negative electrode 4 and the second negative electrode on both sides. The stacking order is as follows: mixed separator 3, first negative electrode 4, mixed separator 3, first positive electrode 5, mixed separator 3, second negative electrode, mixed separator 3, second positive electrode 6, and so on, stacking a total of 20 layers of positive and negative electrode sheets; The first diaphragm is made of polyethylene or polypropylene, and the porosity of the first diaphragm is greater than 44%. The second separator includes polytetrafluoroethylene, soluble polytetrafluoroethylene, or fluorinated ethylene propylene copolymer. The porosity of the second separator is greater than 85%. The second separator is a microporous film made by calendering, extrusion, or biaxial stretching. The second separator is made of a highly flame-retardant film material, which not only retards flames but also improves battery safety performance. The second diaphragm has better insulation performance, melting point, mechanical strength and hardness than the first diaphragm, achieving the best combination of advantages and disadvantages. At the same time, the two diaphragms made of different materials can be used in a composite or double-layer superposition manner. Step 3: Lead out the tabs of the first positive electrode and the second positive electrode from the battery core, stack them and ultrasonically weld them to form positive electrode tab 21; Step 4: Lead out the tabs of the first negative electrode and the second negative electrode, stack them and ultrasonically weld them to form negative electrode tab 22; Step 5: Preferably, the battery cell 2 is placed into the aluminum-plastic film shell 1, and the top and sides are sealed, with a liquid injection port reserved; the battery cell can also be made into a soft-pack lithium-ion battery; Step 6: Inject electrolyte into the drying room, let it stand for 24 hours, and then perform formation and capacity testing to form a battery.
[0019] Second embodiment: While other technical features remain the same as in the first embodiment, this embodiment adds a through-type connecting rod structure to further improve the structural stability of the battery: 1. A through hole with a diameter of 5mm is pre-punched at the center position of the first negative electrode 4, the first positive electrode 5, the second negative electrode, and the second positive electrode 6. After the battery cell 2 is formed, the positions of the through holes on each electrode are aligned. 2. A clearance hole is formed at the corresponding position of the mixing diaphragm 3 by hot melting. The hole diameter is 4.5 mm, which is slightly smaller than the electrode through hole. 3. In the middle of battery cell 2, the through hole and the clearance hole together form clearance channel 8; 4. Before placing the battery cell 2 into the aluminum-plastic film housing 1, insert an insulating stainless steel connecting rod 7 with a diameter of 4mm into the clearance channel 8. 5. After the battery casing 1 is packaged, the two ends of the connecting rod 7 are fixed to the metal sidewalls on both sides of the casing 1 by laser welding; at this time, an insulating gap is formed between the outer wall of the connecting rod 7 and the inner wall of the clearance channel 8. Tests showed that after 500 charge-discharge cycles, the bulging of the casing 1 was reduced by about 65% compared to the battery without the connecting rod structure, effectively improving the structural stability and safety of the battery. It can be seen that the connecting rod 7 effectively prevents the safety hazards caused by the bulging of the casing 1.
[0020] Supplementary Experimental Data To further verify the technical effects of the present invention, the applicant conducted the following experiments: 1. Comparative Experiment of Physicochemical Properties of Diaphragms Table 1 The results show that the PTFE membrane used in this invention has a lower liquid absorption swelling rate, better thermal stability, and flame retardant properties.
[0021] 2. Electrical performance comparison experiment Two sets of batteries were assembled using the same positive and negative electrodes and electrolyte: Control group: Using conventional PE diaphragm; Experimental group: using the hybrid diaphragm (PE+PTFE) of the present invention.
[0022] The test results are as follows: Table 2 Table 3 The experimental group of batteries exhibited lower internal resistance and better capacity consistency after formation, indicating that the hybrid membrane structure is beneficial for ion conduction and interface stability. Furthermore, the battery of this invention exhibited higher capacity after multiple cycles.
[0023] 3. Low-temperature performance comparison experiment exist Discharge tests were conducted on the following three types of batteries at 20℃: Pure lithium iron phosphate (LFP) battery Pure ternary lithium battery (NCM) This invention relates to a hybrid positive electrode battery (LFP+NCM). The results are as follows: Table 4: The hybrid cathode battery of this invention exhibits significantly better capacity retention at low temperatures than pure LFP batteries and performance close to that of pure NCM batteries, indicating that the second cathode plate plays an effective role in heating and raising the temperature under low-temperature conditions.
[0024] As can be seen from the above embodiments and experimental data, the hybrid safety battery processing method proposed in this invention has the following beneficial effects: Improved low-temperature performance: By introducing a second cathode material with excellent low-temperature performance (such as ternary materials), rapid heating can be achieved in low-temperature environments, significantly improving the charge and discharge efficiency of lithium iron phosphate cathode materials; Enhanced safety: The use of a second separator (such as PTFE) with high melting point, high ignition point, and high porosity effectively prevents thermal shrinkage and combustion of the separator, thereby improving the thermal stability of the battery. Enhanced structural stability: The support of the hybrid diaphragm reduces diaphragm wrinkles and damage; the through-type connecting rod structure effectively suppresses shell bulging. Good electrical performance: Experimental results show that the battery of the present invention performs well in terms of capacity, internal resistance, and cycle performance, and its electrical performance is not sacrificed due to the addition of safety structure.
[0025] Therefore, this invention provides a hybrid safety battery that balances low-temperature performance and safety, as well as its processing method, which has high practical value and promising prospects for application.
[0026] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for processing a hybrid safety battery, characterized in that, Includes the following steps: Step 1: Combine a first diaphragm of a first material and a second diaphragm of a second material by overlapping and winding them together to form a hybrid diaphragm; wherein the melting point, insulation performance and hardness of the second diaphragm are all greater than those of the first diaphragm; Step 2: The first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode are stacked layer by layer using a hybrid separator, and the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode are alternately stacked to form a battery cell; wherein, the first positive electrode is made of lithium iron phosphate, and the second positive electrode is made of at least one of the following materials with better low-temperature performance than the first positive electrode: ternary material, lithium cobalt oxide, lithium manganese oxide, sodium iron sulfate, or sodium vanadium phosphate; the second positive electrode heats up before the first positive electrode in a low-temperature environment to heat the first positive electrode and improve its low-temperature charge and discharge efficiency; Step 3: Extend the tabs of the first positive electrode and the second positive electrode from the battery core and stack them together to form a positive electrode tab; Step 4: Extend the tabs of the first negative electrode and the second negative electrode from the battery cell and stack them together to form a negative electrode tab; Step 5: Place the battery cell into the aluminum-plastic film casing, seal it, and leave a liquid injection port; Step 6: Inject electrolyte to form a battery.
2. The processing method of the hybrid safety battery according to claim 1, characterized in that: The first negative electrode and the second negative electrode are both made of carbon; the second positive electrode is made of ternary material.
3. The processing method of the hybrid safety battery according to claim 1, characterized in that: The first diaphragm is made of polyethylene or polypropylene, and the second diaphragm includes polytetrafluoroethylene, soluble polytetrafluoroethylene, or fluorinated ethylene propylene copolymer.
4. The processing method of the hybrid safety battery according to claim 3, characterized in that: The porosity of the first diaphragm is greater than 44%, and the porosity of the second diaphragm is greater than 85%.
5. The processing method of the hybrid safety battery according to claim 3, characterized in that: The second diaphragm is a microporous film made by calendering, extrusion or biaxial stretching.
6. The processing method of the hybrid safety battery according to claim 1, characterized in that: The mixing membrane is disposed between the first positive electrode and the first negative electrode and the second negative electrode on both sides, and the mixing membrane is disposed between the second positive electrode and the first negative electrode and the second negative electrode on both sides.
7. The processing method of the hybrid safety battery according to claim 1, characterized in that: A through hole is pre-drilled in the middle of the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode, and the through holes of the first negative electrode, the first positive electrode, the second negative electrode, and the second positive electrode correspond to each other; The first and second diaphragms are heat-fused at the corresponding through-hole positions to form a clearance hole; The through hole and the clearance hole are interconnected, thus forming a clearance channel; A connecting rod is pre-installed through the clearance channel, and after the battery cell is packaged in the casing, the two ends of the connecting rod are laser-welded to the two side walls of the metal casing.
8. The processing method of the hybrid safety battery according to claim 7, characterized in that: An insulating gap or insulating material is provided between the outer wall of the connecting rod and the inner wall of the clearance channel.
9. The processing method of the hybrid safety battery according to claim 1, characterized in that: It is made by combining diaphragms or by using a composite process / intermittent composite process.
10. A hybrid safety battery, characterized in that: This includes batteries manufactured by any of the processing methods described in claims 1 to 9.