Cylindrical sodium ion battery for starting and stopping power supply

Abstract

The invention relates to the technical field of batteries, in particular to a cylindrical sodium ion battery for starting and stopping a power supply, which comprises a positive pole piece, a negative pole piece, a positive pole piece and a negative pole piece, the negative pole piece, the carbon-coated aluminum foil current collector and the hard carbon / soft carbon composite material are active substances; according to the present invention, with the sodium ion electrolyte, the tab, the steel shell and the cap, the rapidly-charged low-temperature-resistant cylindrical sodium ion battery can be obtained, has the capacity of 1500 mAh, can be subjected to 3C charging and 30C discharging, has the capacity retention rate of more than 80% after 1000 cycles, and can maintain the discharge capacity of 85% at the temperature of-40 DEG C.

Description

Technical Field

[0001] The invention relates to the technical field of batteries, and in particular to a cylindrical sodium ion battery for a start-stop power supply. Background Art

[0002] The fuel consumption standards and exhaust emission requirements for automobiles are becoming increasingly stringent, and the start-stop system has gradually become a standard configuration for passenger cars. As the core component of the start-stop system, the electrochemical performance of the start-stop power supply is directly related to the stability of the start-stop system. The current start-stop power supply market is mainly dominated by lead-acid batteries, and a small part is lithium-ion batteries. The shortcomings of the current start-stop power supply are low capacity, heavy weight and poor low-temperature performance of lead-acid batteries, while lithium-ion start-stop batteries have poor rate and low-temperature performance. Sodium, as an alkali metal element of the same main group as lithium, has the advantages of abundant resources, low price, and similar embedding mechanism. Sodium-ion batteries are gradually becoming a substitute for lithium-ion batteries in some fields. Studies have shown that sodium-ion batteries have better low-temperature and rate performance, and their safety performance is higher than that of lithium-ion batteries. Therefore, the development and utilization of sodium-ion batteries in the direction of start-stop power supplies is a hot direction. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a cylindrical sodium ion battery for start-stop power supply that has both high rate and low temperature properties.

[0004] The present invention is realized by the following technical scheme: a cylindrical sodium ion battery for start-stop power supply, comprising: Positive electrode sheet, including positive electrode coated aluminum foil current collector, composite nickel iron sodium manganese oxide as active material, P2 phase accounts for 45% to 60%, P3 phase accounts for 55% to 40%; A negative electrode sheet, including a negative electrode carbon-coated aluminum foil current collector, and a hard carbon / soft carbon composite material as an active material; Sodium ion electrolyte, tabs, steel shell, cap; With 1500mAh capacity; 3C charging and 30C intermittent discharge; After 1000 cycles, the capacity retention rate is above 80%; Maintain 80% of discharge capacity at -40℃.

[0005] Furthermore, a graphene-SP-CNT composite conductive agent is selected as the conductive agent.

[0006] Furthermore, polyvinylidene fluoride is selected as the positive electrode binder.

[0007] Furthermore, sodium carboxymethyl cellulose (CMC-Na) and sodium polyacrylate (NaPAA) are selected as negative electrode binders.

[0008] Furthermore, in the positive electrode plate, the composite sodium nickel iron manganese oxide is coated with a fast ion conductor sodium fluoroborate coating with a thickness of 3 to 10 nm.

[0009] Furthermore, in the positive electrode plate, the fast ion conductor sodium fluoroborate is prepared by a liquid phase process.

[0010] A preparation process of a positive electrode material composite nickel iron sodium manganese oxide comprises the following steps: Step 1, weighing nickel acetate, iron oxalate, manganese acetate, and anhydrous sodium carbonate and dissolving them in deionized water, and dispersing them by combining mechanical stirring and ultrasonic dispersion to obtain a dispersed material; Step 2, adding sodium carboxymethyl cellulose to the dispersed material under mechanical stirring and ultrasonic dispersion working conditions, stirring for 2 to 4 hours to form a colloidal mixture, and controlling the pH value between 8 and 9 during the stirring process; Step 3, placing the gelatinous mixture into a vacuum freeze dryer for first freezing and then vacuum drying to obtain a gel mixture; Step 4, placing the gel mixture in a tubular furnace, first treating it at 250-300° C. in a nitrogen atmosphere for 3-4 hours to pyrolyze and carbonize the sodium carboxymethyl cellulose to form an amorphous carbon layer, then heating it at a heating rate of 5° C. to 10° C. / min, and sintering it at 850-1000° C. in an oxygen atmosphere for 10-12 hours to obtain a sintered product; Step 5: Transfer the sintered product to a cooling chamber and cool it with low-temperature nitrogen at -40°C to -20°C at a cooling rate of 200 to 300°C / min, and cool it to room temperature to obtain a sintered block; Step six, putting the sintered block into a ball mill, and obtaining composite sodium nickel iron manganese oxide with a particle size of 3 μm to 20 μm after ball milling.

[0011] The beneficial effects of the present invention are: the positive electrode coated aluminum foil current collector, composite nickel iron manganese oxide sodium as the active material, the P2 phase accounts for 45% to 60%, and the P3 phase accounts for 55% to 40%. This is because the P2 phase contains more Na+ vacancies and a relatively low Na+ diffusion barrier, and usually exhibits better kinetic performance, which can improve the rate performance of sodium electricity, and can obtain a fast-charging and low-temperature resistant cylindrical sodium ion battery with a capacity of 1500mAh, which can be charged at 3C and discharged at 30C. After 1000 cycles, the capacity retention rate is above 80%, and the discharge capacity can be maintained at 85% at -40°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a schematic diagram of the rate curve of the battery; Figure 2 Schematic diagram of battery cycle performance; Figure 3Schematic diagram of the low temperature performance of the battery. DETAILED DESCRIPTION

[0013] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0014] The following will be combined with the drawings in the embodiments of the invention to clearly and completely describe the technical solutions in the embodiments of the invention. Obviously, the described embodiments are only part of the embodiments of the invention, not all of the embodiments. Based on the embodiments of the invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the invention.

[0015] Example 1 like Figure 1-3 As shown, a cylindrical sodium ion battery for start-stop power supply, a positive electrode sheet, a negative electrode sheet, a sodium ion electrolyte, a tab, a steel shell, and a cap.

[0016] in, The positive electrode sheet includes a positive electrode coated aluminum foil current collector and a composite sodium nickel iron manganese oxide as an active material. The P2 phase accounts for 58.5% and the P3 phase accounts for 41.5%. This is because the P2 phase material contains more Na+ vacancies and a relatively low Na+ diffusion barrier, and usually exhibits better kinetic properties, which can improve the rate performance of sodium batteries. The P2 phase sodium nickel iron manganese oxide has a dual-phase structure of P2 and P3 phases, in which the P2 phase accounts for 58.5%. The dual-phase structure can The excellent rate performance of the P2 phase and the high stability of the P3 phase are combined to further improve the material's high-rate cycling performance, and the capacity can be maintained at more than 80% after 1000 cycles of 3C-30C. In addition, the P2 phase composite sodium nickel iron manganese oxide is coated with a fast ion conductor sodium fluoroborate coating with a thickness of 3 to 10 nm. In the positive electrode sheet, the fast ion conductor sodium fluoroborate is prepared by a liquid phase process, which can promote the embedding and extraction rate of sodium ions in the electrode material, improve conductivity, and improve the low-temperature performance of sodium ion batteries, achieving a discharge capacity of more than 80% at -40°C. The preparation process of the positive electrode material composite nickel iron sodium manganese oxide comprises the following steps: Step 1, weighing nickel acetate Ni(CH3COO)2·4H2O, iron oxalate Fe2(C2O4)3·5H2O, manganese acetate Mn(CH3COO)2·4H2O, and anhydrous sodium carbonate Na2CO3 and dissolving them in deionized water, and dispersing them by combining mechanical stirring and ultrasonic dispersion to obtain a dispersed material; Step 2, adding sodium carboxymethyl cellulose to the dispersed material under mechanical stirring and ultrasonic dispersion working conditions, stirring for 2 to 4 hours to form a colloidal mixture, and controlling the pH value between 8 and 9 during the stirring process; Step 3, placing the gelatinous mixture into a vacuum freeze dryer for first freezing and then vacuum drying to obtain a gel mixture; Step 4, placing the gel mixture in a tubular furnace, first treating it at 250-300° C. in a nitrogen atmosphere for 3-4 hours to pyrolyze and carbonize the sodium carboxymethyl cellulose to form an amorphous carbon layer, then heating it at a heating rate of 5° C. to 10° C. / min, and sintering it at 850-1000° C. in an oxygen atmosphere for 10-12 hours to obtain a sintered product; Step 5: Transfer the sintered product to a cooling chamber and cool it with low-temperature nitrogen at -40°C to -20°C at a cooling rate of 200 to 300°C / min, and cool it to room temperature to obtain a sintered block; Step 6: Put the sintered block into a ball mill to obtain composite sodium nickel iron manganese oxide NaNi with a particle size of 3 μm to 20 μm. 0.6 Fe 0.2 Mn 0.2 O2.

[0017] A negative electrode sheet, including a negative electrode carbon-coated aluminum foil current collector, a hard carbon / soft carbon composite material as an active material, and a hard carbon and soft carbon composite negative electrode material, which has both the high rate performance of soft carbon and the long cycle life characteristics of hard carbon, and achieves 30C intermittent discharge of more than 1000 weeks. In the field of sodium ion batteries, the compaction density of hard carbon negative electrode sheets is much lower than that of graphite, which is a key factor restricting the large-scale application of negative electrode materials for sodium batteries. In this embodiment, in order to improve the compaction density of the negative electrode sheet, hard carbon and soft carbon are reasonably matched, and different particle size materials are filled with each other. At the same time, a chain polymer binder sodium polyacrylate (NaPAA) is used to reduce the rebound of the electrode sheet after rolling, thereby improving the compaction density of the positive electrode of the negative electrode; The positive and negative electrodes are made of graphene-SP-CNT composite conductive agent, in which SP is grape ball granular conductive graphite, CNT is linear carbon nanotube, and graphene is lamellar single-layer graphite. Through point-line-surface, a three-dimensional conductive network is formed to reduce the resistance of electron transfer, thereby reducing the ohmic internal resistance and polarization internal resistance of the sodium ion battery. For high-rate charging and discharging, an electrolyte with a high sodium ion concentration is used. At the same time, the solvent of the electrolyte uses propylene carbonate with good low-temperature resistance, thereby improving the low-temperature performance of the sodium-ion battery and maintaining 85% of the discharge capacity at -40°C.

[0018] Polyvinylidene fluoride (PVDF) is the positive electrode binder; Sodium carboxymethyl cellulose (CMC-Na) and sodium polyacrylate (NaPAA) are negative electrode binders.

[0019] The test results are attached. Figure 1-3 .

[0020] The compaction density of hard carbon negative electrode sheets is much lower than that of graphite, which is a key factor restricting the large-scale application of negative electrode materials for sodium batteries. In order to improve the compaction density of negative electrode sheets in the embodiments, hard carbon and soft carbon are reasonably matched, and materials of different particle sizes are filled with each other. At the same time, a chain polymer binder sodium polyacrylate (NaPAA) is used to reduce the rebound of the electrode sheets after rolling, thereby improving the compaction density of the positive electrode of the negative electrode.

[0021] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A cylindrical sodium ion battery for start-stop power supply, characterized in that: include, Positive electrode sheet, including positive electrode coated aluminum foil current collector, composite nickel iron sodium manganese oxide as active material, P2 phase accounts for 45% to 60%, P3 phase accounts for 55% to 40%; A negative electrode sheet, including a negative electrode carbon-coated aluminum foil current collector, and a hard carbon / soft carbon composite material as an active material; Sodium ion electrolyte, tabs, steel shell, cap; With 1500mAh capacity; 3C charging and 30C intermittent discharge; After 1000 cycles, the capacity retention rate is above 80%; Maintain 80% of discharge capacity at -40℃.

2. The cylindrical sodium ion battery for start-stop power supply according to claim 1, characterized in that: Graphene-SP-CNT composite conductive agent is selected as the conductive agent.

3. The cylindrical sodium ion battery for start-stop power supply according to claim 1, characterized in that: Polyvinylidene fluoride is selected as the positive electrode binder.

4. The cylindrical sodium ion battery for start-stop power supply according to claim 1, characterized in that: Sodium carboxymethyl cellulose (CMC-Na) and sodium polyacrylate (NaPAA) are selected as negative electrode binders.

5. The cylindrical sodium ion battery for start-stop power supply according to claim 1, characterized in that: In the positive electrode plate, the composite sodium nickel iron manganate is coated with a fast ion conductor sodium fluoroborate coating with a thickness of 3 to 10 nm.

6. The cylindrical sodium ion battery for start-stop power supply according to claim 5, characterized in that: In the positive electrode plate, the fast ion conductor sodium fluoroborate is prepared by a liquid phase process.

7. A preparation process of a positive electrode material composite nickel iron sodium manganese oxide, characterized in that: The following steps are included: Step 1, weighing nickel acetate, iron oxalate, manganese acetate, and anhydrous sodium carbonate and dissolving them in deionized water, and dispersing them by combining mechanical stirring and ultrasonic dispersion to obtain a dispersed material; Step 2, adding sodium carboxymethyl cellulose to the dispersed material under mechanical stirring and ultrasonic dispersion working conditions, stirring for 2 to 4 hours to form a colloidal mixture, and controlling the pH value between 8 and 9 during the stirring process; Step 3, placing the gelatinous mixture into a vacuum freeze dryer for first freezing and then vacuum drying to obtain a gel mixture; Step 4, placing the gel mixture in a tubular furnace, first treating it at 250-300° C. in a nitrogen atmosphere for 3-4 hours to pyrolyze and carbonize the sodium carboxymethyl cellulose to form an amorphous carbon layer, then heating it at a heating rate of 5° C. to 10° C. / min, and sintering it at 850-1000° C. in an oxygen atmosphere for 10-12 hours to obtain a sintered product; Step 5: Transfer the sintered product to a cooling chamber and cool it with low-temperature nitrogen at -40°C to -20°C at a cooling rate of 200 to 300°C / min, and cool it to room temperature to obtain a sintered block; Step six, putting the sintered block into a ball mill, and obtaining composite sodium nickel iron manganese oxide with a particle size of 3 μm to 20 μm after ball milling.

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