Preparation method of ultralow-temperature parking sodium-ion battery system
By modifying the cathode material of sodium-ion batteries and using a refined assembly process, an ultra-low temperature parking sodium-ion battery system with a capacity retention rate of up to 85% at -40℃ was prepared, solving the problem of poor battery performance in low-temperature environments and realizing the application of parking batteries with high safety and long life.
Patent Information
- Application Number
- CN202511885360.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-02-27
AI Technical Summary
Existing parking batteries perform poorly in low-temperature environments, especially lithium-ion batteries, whose capacity retention rate decreases below -10°C, failing to meet the winter parking needs of cold northern regions. Sodium-ion batteries also face technical bottlenecks in capacity output and safety protection at ultra-low temperatures.
Sodium-ion battery cells were prepared using layered oxide Na(NiFeMn)O2 doped with sodium iron phosphate derivatives as the positive electrode material, and battery modules were formed by laser welding. Combined with components such as battery management protection board and safety valve, they were assembled into an ultra-low temperature parking sodium-ion battery system.
Sodium-ion batteries retain up to 85% of their capacity at -40℃, far superior to lithium-ion batteries. They possess high specific energy, long lifespan, and high safety, meeting the demands of long-term high-power power consumption and making them suitable for parking in cold northern regions during winter.
Smart Images
Figure CN121584035A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of sodium-ion battery technology, and specifically relates to a method for preparing an ultra-low temperature parking sodium-ion battery system. Background Technology
[0002] According to statistics from the China Association of Automobile Manufacturers, domestic sales of heavy-duty trucks reached 901,700 units in 2024, with the total number of heavy-duty trucks exceeding 8 million. Among them, about 30% of heavy-duty truck users need to install parking air conditioners and household electrical equipment. Therefore, parking batteries have become an essential component, mainly used to meet the power needs of equipment such as air conditioners, refrigerators, and rice cookers, in order to reduce idling energy consumption and operating costs. Currently, parking batteries on the market are mainly divided into two categories: one is traditional lead-acid batteries, which have obvious defects, including short parking power supply time (usually less than 8 hours), short service life (average 1-1.5 years), easy to deplete and difficult to recover after depletion, requiring frequent replacement and increasing user costs; the other is lithium-ion batteries, which have improved capacity and lifespan, but have poor low-temperature performance. At -10℃, the capacity retention rate drops to below 60%, and below -20℃, they basically cannot discharge normally, which cannot meet the parking needs of cold northern regions in winter. Sodium-ion batteries have become a new direction for parking batteries due to their abundant resources, low cost, and excellent low-temperature performance potential. However, existing sodium battery systems still face technical bottlenecks in terms of capacity output, safety protection, and system integration at ultra-low temperatures (-40℃). There is an urgent need for a method to prepare a parking sodium-ion battery system that can achieve ultra-low temperature adaptability, long range, and high safety. Summary of the Invention
[0003] To address the aforementioned problems in the prior art, this invention provides a method for preparing an ultra-low temperature parking sodium-ion battery system, comprising the following steps: S1. Preparation of sodium-ion battery cell: Based on layered oxide Na(NiFeMn)O2 as the positive electrode material, a certain proportion of composite iron sodium phosphate derivative (chemical formula Na4Fe3(PO4)2P2O7, English abbreviation NFPP) is doped for modification treatment, and a square aluminum shell is used for packaging to make a sodium-ion battery cell with a capacity of 190AH. S2. Battery module manufacturing: Select sodium-ion cells with voltage deviation within ±0.01V and internal resistance deviation within ±0.05mΩ. Connect 8 sodium-ion cells in series in a 2×4 arrangement. Fix them with insulating end plates and steel strips. Weld the positive and negative electrodes through the cell connection system (CCS) to form a battery module. The battery module is qualified if the terminal voltage of the battery module is 8 times the average voltage of a single sodium-ion cell. S3. Assemble the battery system: Fix the battery module and battery management protection board on the metal bracket, connect the soft copper busbar and the wire harness acquisition line, and verify the voltage between the positive output terminal of the battery system and the current sampling terminal (P-) of the battery management protection board; assemble the battery module into the metal box, install the wiring terminal, safety valve, forced start switch and 4G communication module on the box cover, and affix the label after sealing and fixing.
[0004] Preferably, in step S1, the doping ratio of the composite sodium iron phosphate derivative (NFPP) is 20~40%, the size of the square aluminum shell is 71×174×207mm, and the electrode tab and current collector are fully contacted by laser welding to ensure that the contact resistance between the electrode tab and the current collector is ≤0.1mΩ, supporting 3C continuous discharge and 6C pulse discharge, and meeting the requirements of parking time and instantaneous high power of low temperature starting system.
[0005] Specifically, using layered oxide Na(NiFeMn)O2 as the base cathode material, the intrinsic ionic conductivity of the material is improved by doping with 20-40% of a composite sodium iron phosphate derivative (NFPP). Experimental data show that this material can still maintain more than 85% of its capacity output at -40℃, which is 30% better than the low-temperature performance of traditional lithium iron phosphate materials, effectively meeting the requirements of low-temperature discharge.
[0006] Preferably, step S2 includes the following sub-steps: S21. Sorting: Sodium-ion cells are sorted and labeled according to the standards of voltage deviation ≤ ±0.01V and internal resistance deviation ≤ ±0.05mΩ. S22. Arrangement: Select 8 sodium-ion cells from the same grade and arrange them in a matrix of 2 rows × 4 columns to form a cell stack. S23. Fixing: Install insulating end plates at both ends of the cell stack, and use high-strength steel strips to fasten and bind the sodium-ion cells to the insulating end plates to form a mechanically stable cell stack. S24. Connection: Using a Cell Contact System (CCS) assembly, the positive and negative electrodes of each sodium-ion cell are welded to the corresponding conductive connecting pieces on the Cell Contact System (CCS) assembly through laser welding process to form an electrical series circuit and form a battery module. S25. Inspection: Measure the terminal voltage V1 between the total positive electrode (B+) and the total negative electrode (B-) of the battery module. V1 should be equal to 8 times the average voltage of a single sodium-ion cell. The deviation should be controlled within ±0.5V. After passing the inspection, the module production is completed.
[0007] Preferably, in step S24, the parameters of the laser welding process are as follows: welding power of 1800W, welding speed of 50mm / s, and weld width of 0.8mm.
[0008] Preferably, step S3 includes the following sub-steps: S31. Bracket fixing: Fix the battery module and its matching battery management protection board obtained in step S2 to the metal bracket with screws, and install the metal bracket as a whole to the preset position on the bottom plate of the battery box. S32. Electrical connection: Use a soft copper busbar to electrically connect the total positive terminal (B+) of the battery module to the positive output terminal of the battery system, and the total negative terminal (B-) of the battery module to the current sampling terminal (P-) of the battery management and protection board, and insert the interface of the sodium-ion cell's wiring harness acquisition line into the corresponding acquisition port on the battery management and protection board. S33. Voltage Verification: Measure the voltage between the positive output terminal of the battery system and the current sampling terminal (P-) of the battery management protection board. The value should match V1 (±0.5V deviation allowed) to verify the correctness of the wiring. S34. Securing the battery module in the enclosure: Place the battery module with completed voltage verification into the battery slot of the metal enclosure and secure it to the battery slot using fasteners. S35. Top cover assembly: Install wiring terminals, safety valves, forced start switches, and 4G communication modules for remote monitoring at the preset positions on the top cover of the metal enclosure; apply insulating boards to the inner side of the top cover in contact with the high-voltage conductor for insulation protection. S36. Final Connection and Sealing: Connect the cables of the main positive terminal (B+) of the battery module and the current sampling terminal (P-) of the battery management protection board from inside the box to the positive terminal on the box cover and tighten them; align the box cover with the battery compartment and seal it with a sealing ring and fastening screws. S37. Labeling: Affix labels containing information such as rated voltage (24V), capacity, polarity, and warnings to a prominent position on the outer surface of the metal casing to complete the preparation of the entire battery system.
[0009] Preferably, in step S31, the battery management protection board has overvoltage protection (upper limit 29.2V), undervoltage protection (lower limit 19.2V), overcurrent protection (300A instantaneous), overheat protection (triggered at 75℃), and intelligent balancing function (balancing current ≥50mA), effectively ensuring the consistency and safety of the battery during charging and discharging.
[0010] Preferably, the specifications of the soft copper busbar in step S32 are as follows: thickness of 2mm and width of 20mm, to ensure efficient current flow and installation effect.
[0011] Preferably, in step S34, the metal box is made of iron material through sheet metal processing, stamping, welding, surface powder coating and screen printing.
[0012] Preferably, in step S35, the wiring terminal adopts a copper integrated output wiring terminal with a rated current of 250A to ensure the battery discharge overcurrent performance and mechanical installation performance; the safety valve adopts an M10 water-blocking and venting safety valve to ensure the internal and external pressure of the battery is balanced and the safety is stronger; the forced start switch adopts an M12 forced start switch to ensure that the battery can be forced to start.
[0013] The beneficial effects of this invention are: (1) Excellent low temperature performance: The use of doped and modified composite sodium iron phosphate cathode material fundamentally improves the migration ability of sodium ions at low temperature, so that the battery system can maintain a capacity of more than 85% at an extreme low temperature of -40℃, which is 30% better than the low temperature performance of traditional lithium iron phosphate material, meeting the low temperature discharge requirements; its low temperature start-up and discharge capabilities are far superior to those of traditional lithium-ion batteries, solving the problem of parking in cold northern regions in winter. (2) Excellent overall performance: The battery system has high specific energy (190Ah large capacity cell), high power characteristics (supports 3C continuous / 6C pulse discharge) and long cycle life, which can meet the long-term, intermittent high power power demand in the parking scenario. (3) High safety and reliability: Through meticulous cell sorting, reliable module structure, and laser welding process, the consistency of the system is guaranteed. The customized battery management protection board realizes comprehensive cell status monitoring and protection. The enclosure is equipped with a water-blocking and ventilating valve to balance internal and external pressure, and a forced start switch is provided as an emergency backup. (4) The process is highly operable: the preparation method provided has clear steps and parameters. Through key quality control points such as sorting and verification, the stability of mass production and yield are ensured, making it easy to achieve industrialization.
[0014] (5) Low cost and long life: Sodium-ion batteries have a cycle life of ≥2000 times, which is 4-5 times longer than lead-acid batteries, reducing user replacement costs. At the same time, sodium resources are abundant, and the material cost is 30% lower than that of lithium batteries. Attached Figure Description
[0015] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0016] Figure 1 This is a process flow diagram of the present invention.
[0017] Figure 2 This is a comparative graph showing the discharge capacity retention rate of the sodium-ion battery prepared in this invention at different temperatures ranging from -40℃ to 55℃. Detailed Implementation
[0018] The present invention will now be clearly described with reference to the accompanying drawings and specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.
[0019] Example Combination Figure 1 As shown in the figure, this invention provides a method for preparing an ultra-low temperature parking sodium-ion battery system, including the following steps: S1. Preparation of sodium-ion battery cells: Take 700g of layered oxide Na(NiFeMn)O2 powder, 300g of NFPP powder (doping ratio 30%), add 50g of polyvinylpyrrolidone and 2000ml of N-methylpyrrolidone, and stir in a high-speed stirrer at 1500r / min for 2 hours to form a uniform slurry. Feed the slurry into a spray dryer, setting the inlet air temperature to 200℃ and the outlet air temperature to 80℃ to obtain the modified cathode material powder.
[0020] The modified positive electrode material powder was mixed with conductive carbon black (100g) and polyvinylidene fluoride (50g), and N-methylpyrrolidone was added to form a slurry. This slurry was coated onto aluminum foil (12μm thick), dried at 120℃, rolled (compacted density 3.2g / cm³), and then cut into positive electrode sheets with a length of 170mm and a width of 68mm. The negative electrode sheet, using hard carbon as the active material, was prepared using the same process and cut into negative electrode sheets with a length of 172mm and a width of 70mm.
[0021] A 71×174×207mm square aluminum shell is used to wind the positive electrode, separator, and negative electrode into a core package. After vacuum sealing, 150ml of electrolyte is injected for formation treatment to produce a 190AH battery cell. The tabs and current collector are laser-welded. After welding, the contact resistance is measured to be 0.08mΩ, and no abnormalities are found in the 3C discharge test.
[0022] S2. Manufacturing the battery module, including the following sub-steps: S21. Sorting: Sodium-ion cells are sorted and labeled according to the standards of voltage deviation ≤ ±0.01V and internal resistance deviation ≤ ±0.05mΩ. S22. Arrangement: Select 8 sodium-ion cells from the same grade and arrange them in a matrix of 2 rows × 4 columns to form a cell stack. S23. Fixing: Install insulating end plates at both ends of the cell stack, and use high-strength steel strips to fasten and bind the sodium-ion cells to the insulating end plates to form a mechanically stable cell stack. S24. Connection: Using a Cell Connection System (CCS) assembly, the positive and negative electrodes of each sodium-ion cell are welded to the corresponding conductive connecting pieces on the Cell Connection System (CCS) assembly through laser welding process to form an electrical series circuit, thereby forming a battery module. The welding power is 1800W, the welding speed is 50mm / s, and the weld width is 0.8mm. S25. Inspection: Measure the terminal voltage V1 between the total positive electrode (B+) and the total negative electrode (B-) of the battery module. V1 should be equal to 8 times the average voltage of a single sodium-ion cell. The deviation should be controlled within ±0.5V. After passing the inspection, the module production is completed.
[0023] S3. Assemble the battery system, including the following sub-steps: S31. Bracket Fixing: Fix the battery module and its matching battery management protection board obtained in step S2 to the metal bracket with screws, and install the entire metal bracket to the preset position on the bottom plate of the battery box; wherein, the battery management protection board has overvoltage protection (upper limit 29.2V), undervoltage protection (lower limit 19.2V), overcurrent protection (300A instantaneous), overheat protection (triggered at 75℃) and intelligent balancing function (balancing current ≥50mA), effectively ensuring the consistency and safety of the battery during charging and discharging; S32. Electrical connection: Use a soft copper busbar with a thickness of 2mm and a width of 20mm to electrically connect the total positive terminal (B+) of the battery module to the positive output terminal of the battery system, and the total negative terminal (B-) of the battery module to the current sampling terminal (P-) of the battery management and protection board, and insert the interface of the sodium ion cell's wiring harness acquisition line into the corresponding acquisition port on the battery management and protection board. S33. Voltage Verification: Measure the voltage between the positive output terminal of the battery system and the current sampling terminal (P-) of the battery management protection board. The value should match V1 (±0.5V deviation allowed) to verify the correctness of the wiring. S34. Securing the battery module: Place the battery module, after voltage verification, into the battery slot of the metal casing and secure it to the battery slot with fasteners; the metal casing is made of iron material through sheet metal, stamping, welding, surface powder coating and screen printing processes. S35. Top cover assembly: Install a 250A rated current terminal block, an M10 water-blocking and ventilating safety valve, an M12 forced start switch, and a 4G communication module for remote monitoring at the preset position on the top cover of the metal enclosure; and attach an insulating board to the area in contact with the high-voltage conductor on the inside of the top cover for insulation protection. S36. Final Connection and Sealing: Connect the cables of the main positive terminal (B+) of the battery module and the current sampling terminal (P-) of the battery management protection board from inside the box to the positive terminal on the box cover and tighten them; align the box cover with the battery compartment and seal it with a sealing ring and fastening screws. S37. Labeling: Affix labels containing information such as rated voltage (24V), capacity, polarity, and warnings to a prominent position on the outer surface of the metal casing to complete the preparation of the entire battery system. like Figure 2 As shown in the experimental data, the sodium-ion battery prepared by this invention can still maintain more than 85% of its capacity output at -40℃, which is 30% better than the low-temperature performance of traditional lithium iron phosphate batteries, effectively meeting the requirements of low-temperature discharge.
[0024] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.
Claims
1. A method for preparing an ultra-low temperature parking sodium-ion battery system, characterized in that: Includes the following steps: S1. Preparation of sodium-ion battery cell: Using layered oxide Na(NiFeMn)O2 as the base cathode material, a certain proportion of composite iron sodium phosphate derivative is doped for modification treatment, and a square aluminum shell is used for packaging to produce a sodium-ion battery cell with a capacity of 190AH. S2. Battery module manufacturing: Select sodium-ion cells with voltage deviation within ±0.01V and internal resistance deviation within ±0.05mΩ. Connect 8 sodium-ion cells in series in a 2×4 arrangement. Fix them with insulating end plates and steel strips. Weld the positive and negative electrodes through the cell connection system components to form a battery module. The battery module is qualified if the terminal voltage of the battery module is 8 times the average voltage of a single sodium-ion cell. S3. Assemble the battery system: Fix the battery module and battery management protection board on the metal bracket, connect the soft copper busbar and the wire harness acquisition line, and verify the voltage between the positive output terminal of the battery system and the current sampling terminal of the battery management protection board; assemble the battery module into the metal box, install the wiring terminal, safety valve, forced start switch and 4G communication module on the box cover, and affix the label after sealing and fixing.
2. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 1, characterized in that: In step S1, the doping ratio of composite sodium iron phosphate is 20~40%, and the size of the square aluminum shell is 71×174×207mm.
3. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 1, characterized in that: Step S2 includes the following sub-steps: S21. Sorting: Sodium-ion cells are sorted and labeled according to the standards of voltage deviation ≤ ±0.01V and internal resistance deviation ≤ ±0.05mΩ. S22. Arrangement: Select 8 sodium-ion cells from the same grade and arrange them in a matrix of 2 rows × 4 columns to form a cell stack. S23. Fixing: Install insulating end plates at both ends of the cell stack, and use high-strength steel strips to firmly bind the sodium-ion cells to the insulating end plates to form a mechanically stable cell stack. S24. Connection: Using a cell connection system component, the positive and negative electrodes of each sodium-ion cell are welded to the corresponding conductive connecting pieces on the cell connection system component through laser welding process to form an electrical series circuit, thus forming a battery module; S25. Inspection: Measure the terminal voltage V1 between the total positive and total negative terminals of the battery module. V1 should be equal to 8 times the average voltage of a single sodium-ion cell. The deviation should be controlled within ±0.5V. After passing the inspection, the module production is completed.
4. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 3, characterized in that: In step S24, the parameters of the laser welding process are as follows: welding power is 1800W, welding speed is 50mm / s, and weld width is 0.8mm.
5. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 1, characterized in that: Step S3 includes the following sub-steps: S31. Bracket fixing: Fix the battery module and its matching battery management protection board obtained in step S2 to the metal bracket with screws, and install the metal bracket as a whole to the preset position on the bottom plate of the battery box. S32. Electrical connection: Use a soft copper busbar to electrically connect the total positive terminal of the battery module to the positive output terminal of the battery system, and the total negative terminal of the battery module to the current sampling terminal of the battery management and protection board, and insert the interface of the sodium-ion cell's wiring harness acquisition line into the corresponding acquisition port on the battery management and protection board. S33. Voltage Verification: Measure the voltage between the positive output terminal of the battery system and the current sampling terminal of the battery management protection board. The value should match V1 to verify the correctness of the wiring. S34. Securing the battery module in the enclosure: Place the battery module with completed voltage verification into the battery slot of the metal enclosure and secure it to the battery slot using fasteners. S35. Top cover assembly: Install wiring terminals, safety valves, forced start switches, and 4G communication modules for remote monitoring at the preset positions on the top cover of the metal enclosure; apply insulating boards to the inner side of the top cover in contact with the high-voltage conductor for insulation protection. S36. Final connection and sealing: Connect the cables of the main positive terminal of the battery module and the current sampling terminal of the battery management protection board from the box to the positive terminal on the box cover and tighten them; align the box cover with the battery compartment and seal it with a sealing ring and fastening screws. S37. Labeling: Affix labels containing information such as rated voltage, capacity, polarity, and warnings to a prominent position on the outer surface of the metal casing to complete the preparation of the entire battery system.
6. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 5, characterized in that: In step S31, the battery management protection board has overvoltage protection, undervoltage protection, overcurrent protection, overheat protection and intelligent balancing functions.
7. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 5, characterized in that: The specifications of the soft copper busbar in step S32 are as follows: thickness is 2mm and width is 20mm.
8. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 5, characterized in that: In step S34, the metal box is made of iron material through sheet metal processing, stamping, welding, surface powder coating and screen printing.
9. The method for preparing the ultra-low temperature parking sodium-ion battery system according to claim 5, characterized in that: In step S35, the wiring terminal is a copper integrated output wiring terminal with a rated current of 250A, the safety valve is an M10 water-blocking and ventilating safety valve, and the forced start switch is an M12 forced start switch.