CN116169301A - Current collector for sodium ion secondary battery, preparation method and equipment - Google Patents

Abstract

The invention relates to a sodium ion secondary battery, in particular to a current collector for a sodium ion secondary battery, a preparation method and equipment. The positive current collector of the sodium ion secondary battery comprises a metal foil of an intermediate layer, and coatings respectively located on both sides of the intermediate layer; the coating contains nanocellulose and a conductive agent. The positive electrode current collector of the sodium ion secondary battery of the present invention isolates the contact between the positive electrode material of the sodium ion and the aluminum foil, and overcomes the polarity caused by the chemical reaction between the positive electrode material and the aluminum foil in the existing sodium ion secondary battery. The compaction density of the sheet is low, the capacity of the finished battery is reduced, and the service life is reduced.

Description

Current collector for sodium ion secondary battery, preparation method and equipment

technical field

The invention relates to a sodium ion secondary battery, in particular to a current collector for a sodium ion secondary battery, a preparation method and equipment.

Background technique

In the 21st century, lithium batteries are used in many fields such as mobile phones, computers, wearable devices, electric vehicles, two-wheeled bicycles, electric tools, and street lamps. In recent years, the consumption of lithium resources has shown a phenomenon of large usage and fast consumption, and the growth of lithium production cannot meet the growth of consumption: this is because: first, lithium resources are limited, mainly spodumene ore and The state of lithium in salt lake exists, and the second is that lithium in salt lake cannot be extracted in winter. In contrast, sodium has a wide range of sources and abundant reserves. The reserve of sodium is 420 times that of lithium, and its price is much lower than that of lithium. In recent years, with the crazy rise in lithium prices, sodium-ion batteries are expected to cost 30-50% lower than lithium-ion batteries and have attracted widespread attention, especially in the field of energy storage, hybrid power, and the field of replacing lead-acid batteries. It has attractive application prospects.

At present, the preparation method of the positive electrode of the sodium ion battery is: one of the three materials Na ₃ V ₂ (PO ₄ ) ₃ , NaFe _1/3 Ni _1/3 Mn _1/3 O ₃ , and Prussian blue is mixed with a conductive agent, an adhesive The binder is prepared as a slurry and coated on an aluminum foil, and then prepared by drying, rolling, slitting and other processes.

Compared with the positive electrode material of lithium ion secondary battery, the alkalinity of the positive electrode material of sodium ion secondary battery is higher, and a certain chemical reaction occurs between the positive electrode material and the aluminum foil due to contact, which leads to a decrease in the compaction density of the positive electrode sheet during the rolling process, and the positive electrode Material loss leads to a reduction in the capacity of the finished sodium ion secondary battery and a reduction in the cycle life of the battery.

Contents of the invention

The present invention aims at solving one of the technical problems of the prior art at least to a certain extent.

The present invention provides a positive electrode current collector of a sodium ion secondary battery, a preparation method and equipment. The current collector isolates the contact between the positive electrode material of the sodium ion and the aluminum foil, and overcomes the problem of the positive electrode material and the aluminum foil in the existing sodium ion secondary battery. Due to the chemical reaction between the aluminum foils, the compaction density of the pole pieces is low, the capacity of the finished battery is reduced, and the service life is reduced.

A sodium ion secondary battery cathode current collector comprises a metal foil in an intermediate layer and coatings respectively located on both sides of the intermediate layer; the coating contains nanocellulose and a conductive agent.

The current collector of the present invention adopts a three-layer structure, the upper and lower layers are coatings, and the middle is metal foil (such as aluminum foil); the nanocellulose component in the coating prevents the contact between the positive electrode material and the aluminum foil, and prevents chemical reactions between the two ; Since the nanocellulose is non-conductive, a highly conductive component is added to the coating to realize the electronic conduction between the positive electrode material and the current collector.

According to an embodiment of the present invention, the metal foil is selected from aluminum foil or copper foil. Optionally, the metal foil has a thickness of 10-20 μm, such as 15 μm.

According to an embodiment of the present invention, the thickness of the coating is 0.5-5 μm, such as 1-2 μm.

According to an embodiment of the present invention, the coating contains 30-75wt% of nanocellulose, optionally 60-72wt%, and the coating contains 10-40wt% of a conductive agent, optionally 25-37wt%.

According to an embodiment of the present invention, the nanocellulose is selected from one or both of cellulose nanocrystals and cellulose nanofibrils.

Optionally, the cellulose nanocrystals have a diameter of 5-70 nm and a length of 25-300 nm; preferably a diameter of 5-20 nm and a length of 25-100 nm; more preferably a diameter of 15-20 nm and a length of 35-45 nm.

Optionally, the cellulose nanofibrils have a diameter of 5-60 nm and a length of 100-3000 nm; preferably a diameter of 5-20 nm and a length of 500-1500 nm; more preferably a diameter of 5-10 nm and a length of 500-650 nm.

In some embodiments, the nanocellulose is a mixture with cellulose nanofibrils, the mass ratio of the two is 1:1; the diameter of cellulose nanocrystals is 15-20 nm, and the length is 35-45 nm; the diameter of cellulose nanofibrils is 5 nm. -10nm, length 500-650nm.

According to an embodiment of the present invention, the conductive agent is selected from one or more of carbon black, acetylene black, carbon nanotubes, Ketjen black, and carbon fibers; preferably acetylene black and carbon nanotubes, the mass ratio of the two is 1: 1.

According to an embodiment of the present invention, the coating further contains a binder, the content of which may be 1-5wt%, and further may be 2-5wt%.

According to an embodiment of the present invention, the binder is polyvinylidene fluoride (PVDF), preferably with a molecular weight of 800,000-1.2 million, such as 1 million. Studies have found that if the molecular weight of polyvinylidene fluoride is too low, the cohesiveness will be poor, and if the molecular weight is too high, it will be difficult to dissolve.

According to an embodiment of the present invention, the coating further contains a dispersant, the content of which may be 0.5-3wt%, and further may be 1-3wt%.

According to an embodiment of the present invention, the dispersant is polyvinylpyrrolidone (PVP), preferably with a molecular weight of 600,000-1.2 million, such as 800,000. Studies have found that if the molecular weight of polyvinylpyrrolidone is too low, the dispersibility will be poor, and if the molecular weight is too high, it will be difficult to dissolve.

According to an embodiment of the present invention, the raw materials for preparing the coating further include a solvent, which may be N-methylpyrrolidone (NMP). Typically, the solvent in the coating is substantially volatilized after drying.

According to an embodiment of the present invention, the coating contains nanocellulose, a conductive agent, a binder, and a dispersant. Optionally, the mass ratio of the nanocellulose, a conductive agent, a binder, and a dispersant is (30- 75):(10-40):(1-5):(0.5-3).

The present invention also provides a method for preparing the positive electrode current collector of the above-mentioned sodium ion secondary battery, including:

1) mixing the nanocellulose, conductive agent, binder, dispersant and solvent according to the proportioning ratio to prepare a slurry with a solid content of 5-50wt%;

2) The slurry is evenly coated on the upper and lower surfaces of the metal foil, and dried;

3) the metal foil coated in step 2) is oxidized under _NO atmosphere;

4) Hot rolling the oxidized metal foil in step 3) to obtain a current collector.

Optionally, the solid content of the slurry in step 1) is 10-20wt%. If the solid content of the slurry is too low, the manufacturing cost will be high; if the solid content of the slurry is too high, it will be difficult to uniformly disperse various substances.

Optionally, step 1) fully disperse in the Hongyun DL-500L equipment, the linear velocity of the dispersing disc is 10-200m/min, preferably 60-100m/min, if it is too low, it is difficult to fully disperse; if it is too high, it is easy to break the dispersed material; Dispersion time 120-240min.

Optionally, step 2) is coated on a Kejing Zhida Technology MG200 micro-gravure coater. Optionally, the coating speed is 2-10m/min, and the drying temperature is 80-130°C. Optionally, the coating thickness after drying is 0.5-5 μm, further optionally 1-2 μm.

Optionally, in step 3) the NO ₂ flow rate is 10L-30L/min, and the oxidation temperature is 60-120°C. Studies have found that high temperature is conducive to the oxidation reaction. Oxidation can eliminate the hydroxyl groups in the nanocellulose material, preventing it from chemically reacting with the highly oxidized cathode material after the battery is charged.

Optionally, the pressure of step 4) hot rolling is 0.1-2 MPa, and the temperature of hot rolling is 60-80°C. Hot rolling is beneficial to enhance the bonding force between the coating and the metal foil.

In some specific examples, the preparation method of the positive electrode current collector of the sodium ion secondary battery includes:

1) Fully disperse nanocellulose, conductive agent, binder, dispersant and solvent in Hongyun DL-500L equipment according to the ratio to make a slurry with a solid content of 5-50wt%; the linear speed of the dispersion disc is 10- 200m/min, preferably 60-100m/min, dispersion time 120-240min;

2) The slurry is evenly coated on the upper and lower surfaces of the metal foil on the Kejing Zhida Technology MG200 micro-gravure coating machine, the coating speed is 2-10m/min, and the drying temperature is 80-130°C; The thickness of the back coating is 0.5-5 μm, preferably 1-2 μm;

3) Oxidize the metal foil coated in step 2) under NO ₂ atmosphere; NO ₂ flow rate 10L-30L/min, oxidation temperature 60-120°C;

4) hot-rolling the oxidized metal foil in step 3) to obtain a current collector; the pressure of the hot-rolling is 0.1-2 MPa, and the temperature of the hot-rolling is 60-80°C.

In order to better prepare the positive electrode current collector of the above-mentioned sodium ion secondary battery, the present invention also provides a kind of equipment, including the unwinding shaft connected in sequence; the transfer shaft; the first micro-gravure coating machine; the first oven; the second micro-gravure coating Cloth machine; second oven; NO ₂ oxidation equipment; hot pressing roller; winding shaft. Among them, NO ₂ oxidation equipment is provided with NO ₂ outlet and NO ₂ inlet.

The present invention also includes the positive current collector of the sodium ion secondary battery prepared by the above method.

The present invention also includes the application of the above-mentioned positive electrode current collector of the sodium ion secondary battery in the preparation of the sodium ion secondary battery.

The present invention also provides a positive pole piece of a sodium ion secondary battery, comprising the above-mentioned positive current collector of the sodium ion secondary battery. In some examples, a positive electrode slurry coated on the positive electrode current collector is also included. Optionally, the positive electrode slurry includes one or more of NaFe _1/3 Ni _1/3 Mn _1/3 O ₃ , sodium vanadium phosphate, sodium vanadium fluorophosphate, Prussian white, and the like.

The present invention also provides a sodium-ion secondary battery, comprising the above-mentioned positive pole piece of the sodium-ion secondary battery; or comprising the above-mentioned positive current collector of the sodium-ion secondary battery.

The nanocellulose in the coating of the present invention isolates the contact between the positive electrode material and the aluminum foil, preventing the chemical reaction between the two; compared with the sodium ion secondary battery using the traditional aluminum foil as the positive electrode current collector, the present invention The compacted density of the cathode sheet of the sodium-ion secondary battery prepared by the invention is increased by 0.1-0.3g/cm3, the capacity of the prepared sodium-ion battery is increased by 20-30%, and the cycle life is increased by 70-110%.

Description of drawings

Fig. 1 is a schematic diagram of a positive current collector of a sodium ion secondary battery according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of equipment for preparing a positive electrode collector for a sodium ion secondary battery according to an embodiment of the present invention.

Detailed ways

The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field, or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that can be purchased through formal channels.

It should be noted that terms such as "first" and "second" are used for descriptive purposes only, and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, a feature defined as "first", "second", etc. may expressly or implicitly include one or more of that feature. Further, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

As shown in Fig. 1, the embodiment of the present invention provides a kind of positive electrode current collector of sodium ion secondary battery, comprises middle layer metal foil 2, and coating 1 and 3 respectively positioned at the both sides of described middle layer; Said coating contains Nanocellulose and conductive agent.

As shown in Figure 2, the embodiment of the present invention provides a kind of equipment that prepares the positive current collector of sodium ion secondary battery, comprises unwinding reel 1 connected in sequence; Transfer shaft 2; First micro-gravure coater 3; First oven 4 ; The second micro-gravure coating machine 5; The second oven 6; NO ₂ oxidation equipment 7; Hot pressing roller 10; Wherein, NO ₂ oxidation equipment 7 is provided with NO ₂ gas outlet 8 and NO ₂ gas inlet 9 .

As shown in Figure 2, the working process of the device is as follows: the aluminum foil is unwinded on the unwinding reel 1; it is sent to the first micro-gravure coating machine 3 through the transfer reel 2, and the slurry (cellulose) is coated on the upper surface of the aluminum foil. slurry) and dried by the first oven 4; then enter the second micro-gravure coater 5, coat the slurry (cellulose slurry) on the lower surface of the aluminum foil, and be dried by the second oven 6; then in the NO _2. Oxidize the cellulose in the oxidation device 7; then perform rolling treatment at the hot pressing roller 10; and wind at the winding shaft 11.

In some embodiments, the coated slurry can be prepared from the following examples, or the slurry prepared by the prior art can also be used.

The following cathode current collectors for sodium ion secondary batteries can be prepared using the equipment shown in FIG. 2 .

Example 1

This embodiment provides a current collector for the positive electrode of a sodium ion secondary battery, and the preparation method is as follows:

1) Nanocellulose, conductive agent, binder, and dispersant are added to NMP in a mass ratio of 72:25:2:1, and fully dispersed in Hongyun DL-500L equipment to prepare a slurry with a solid content of 10%; The linear speed of the dispersing disc is 75m/min, and the dispersing time is 180min;

Nanocellulose is cellulose nanocrystals with a diameter of 15-20nm and a length of 35-45nm; the conductive agent is acetylene black with a particle size distribution of 35-45nm; the binder is PVDF with a molecular weight of 1 million; the dispersant is PVP with a molecular weight of 800 000;

2) The above slurry is evenly coated on the upper and lower surfaces of 15μm thick aluminum foil on the Kejing Zhida Technology MG200 micro-gravure coating machine, the coating speed is 3m/min, and the drying temperature is 110°C; the coating thickness after drying is 1μm;

3) Step 2) The coated current collector is oxidized under NO ₂ atmosphere, the NO ₂ flow rate is 15L/min; the oxidation temperature is 100°C;

4) The oxidized current collector in step 3) is hot-rolled under a certain pressure, the pressure is 0.25MPa, and the hot-rolling temperature is 80°C.

Example 2

This embodiment provides a current collector for the positive electrode of a sodium ion secondary battery, and the preparation method is as follows:

1) Nanocellulose, conductive agent, binder, and dispersant are added to NMP in a mass ratio of 72:25:2:1, and fully dispersed in Hongyun DL-500L equipment to prepare a slurry with a solid content of 10%; The linear speed of the dispersing disc is 75m/min, and the dispersing time is 180min;

Nanocellulose is a mixture of cellulose nanofibrils, the mass ratio of the two is 1:1; cellulose nanocrystals have a diameter of 15-20nm and a length of 35-45nm; cellulose nanofibrils have a diameter of 5-10nm and a length of 500-650nm ;

The conductive agent is a mixture of acetylene black and carbon nanotubes, the mass ratio of acetylene black to carbon nanotubes is 1:1; the particle size distribution of acetylene black is 35-45nm; the diameter of carbon nanotubes is 5-10mm, and the length is 50-80nm ;The binder is PVDF with a molecular weight of 1 million; the dispersant is PVP with a molecular weight of 800,000;

2) The above slurry is evenly coated on the upper and lower surfaces of 15μm thick aluminum foil on the Kejing Zhida Technology MG200 micro-gravure coating machine, the coating speed is 3m/min, and the drying temperature is 110°C; the coating thickness after drying is 1μm;

3) Step 2) The coated current collector is oxidized under NO ₂ atmosphere, the NO ₂ flow rate is 15L/min; the oxidation temperature is 100°C;

4) The oxidized current collector in step 3) is hot-rolled under a certain pressure, the pressure is 0.25MPa, and the hot-rolling temperature is 80°C.

Example 3

This embodiment provides a current collector for the positive electrode of a sodium ion secondary battery, and the preparation method is as follows:

1) Nanocellulose, conductive agent, binder, and dispersant are added to NMP in a mass ratio of 60:37:2:1, and fully dispersed in Hongyun DL-500L equipment to prepare a slurry with a solid content of 10%; The linear speed of the dispersing disc is 75m/min, and the dispersing time is 180min;

Nanocellulose is a mixture of cellulose nanofibrils, the mass ratio of the two is 1:1; cellulose nanocrystals have a diameter of 15-20nm and a length of 35-45nm; cellulose nanofibrils have a diameter of 5-10nm and a length of 500-650nm The conductive agent is a mixture of acetylene black and carbon nanotubes, the mass ratio of acetylene black to carbon nanotubes is 1:1; the particle size distribution of acetylene black is 35-45nm; the diameter of carbon nanotubes is 5-10mm, and the length is 50- 80nm; the binder is PVDF with a molecular weight of 1 million; the dispersant is PVP with a molecular weight of 800,000;

2) The above slurry is evenly coated on the upper and lower surfaces of 15μm thick aluminum foil on the Kejing Zhida Technology MG200 micro-gravure coating machine, the coating speed is 3m/min, and the drying temperature is 110°C; the coating thickness after drying is 1μm;

3) Step 2) The coated current collector is oxidized under NO ₂ atmosphere, the NO ₂ flow rate is 15L/min; the oxidation temperature is 100°C;

4) The oxidized current collector in step 3) is hot-rolled under a certain pressure, the pressure is 0.25MPa, and the hot-rolling temperature is 80°C.

Comparative example 1

The positive current collector of the sodium ion secondary battery differs from that of Example 1 only in that the mass ratio of nanocellulose, conductive agent, binder, and dispersant is 92:5:2:1.

Comparative example 2

The positive electrode current collector of the sodium ion secondary battery differs from Example 1 only in that the mass ratio of nanocellulose, conductive agent, binder, and dispersant is 10:87:2:1.

Experimental example

The NaFe _1/3 Ni _1/3 Mn _1/3 O ₃ cathode slurry is respectively coated on the current collectors for sodium ion secondary batteries prepared in Example 1-3 and Comparative Example 1-2, and the common Aluminum foil (Guangzhou Nano New Material Technology Co., Ltd. 1060 aluminum foil, thickness 15 μm), dried at 95 ° C, rolled to obtain positive pole pieces, further cut and wound to obtain 26650 cylindrical sodium ion secondary batteries. In terms of mass fraction, the proportion of the positive pole piece is: NaFe _1/3 Ni _1/3 Mn _1/3 O ₃ 94%, Super P 3%, PVDF 3%.

Among them, the test method for the maximum compaction density of the pole piece: cut the coated pole piece into a size of 200×200mm, set the pressure of the roller press to 30-60 tons, and perform rolling. After rolling, the pole piece is folded in half. The pole piece corresponding to no fracture is compacted, which is the maximum compaction of the pole piece.

Electrode impedance test method: Cut the rolled electrode into a square size of 4cm×8cm, place the cut electrode between the probes of the BER2200 tester, apply a pressure of 5MPa, and read the value.

Battery internal resistance test method: Use the RJ3563 internal resistance tester to test the internal resistance of the battery under the condition of 1000Hz.

For the prepared batteries, five batteries were taken out for each scheme to carry out cycle tests at 25°C for N cycles, and the discharge capacities of the N and 1 cells were recorded, and the discharge retention rate was calculated. Discharge retention rate = Nth discharge capacity/1st discharge capacity × 100%, when the cycle discharge retention rate is 80%, the cycle test is terminated, and the number of cycles is recorded. The test results are shown in Table 1.

Table 1 performance test results

As can be seen from the above table, compared with the sodium ion secondary battery prepared by using the traditional aluminum foil, the maximum compaction density of the positive pole piece, the battery capacity and the cycle life of the sodium ion secondary battery prepared by the current collector of the present invention have been significantly improved. Improvement; the maximum compaction density, battery capacity and cycle life of the battery using the composite nanocellulose solution are slightly better than those of a single nanocellulose battery; increasing the conductive agent content in the current collector coating can continue to improve the cycle life of the battery .

As can be seen from Example 1 and Comparative Example 1, the addition of too much polyacrylonitrile increases the maximum compacted density of the pole piece, but because of the poor conductivity, the battery capacity decreases and the cycle life deteriorates; from Example 1 and Comparative Example 1 From comparative example 2, it can be seen that too little polyacrylonitrile is added, the maximum compacted density of the pole piece decreases, and the alkali resistance deteriorates, resulting in an increase in the impedance of the pole piece, a decrease in battery capacity, and a poor cycle life.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (10)

1. a sodium ion secondary battery positive electrode current collector, is characterized in that, comprises interlayer metal foil, and is respectively positioned at the coating of described interlayer both sides; Described coating contains nanocellulose and conductive agent; Optional Optionally, the metal foil is selected from aluminum foil or copper foil; and/or, optionally, the thickness of the metal foil is 10-20 μm; and/or, the thickness of the coating is 0.5-5 μm. 2. sodium ion secondary battery cathode current collector according to claim 1, is characterized in that, contains nano-cellulose 30-75wt% in the described coating, can be selected as 60-72wt%; Conductive agent 10-40wt%, optionally 25-37wt%; Optionally, the nanocellulose is selected from one or both of cellulose nanocrystals and cellulose nanofibrils; Optionally, the conductive agent is selected from one or more of carbon black, acetylene black, carbon nanotubes, Ketjen black, and carbon fibers; preferably acetylene black and carbon nanotubes, the mass ratio of the two is 1:1. 3. the sodium ion secondary battery positive electrode current collector according to claim 1 or 2, is characterized in that, The coating also contains a binder, the content of which may be 1-5wt%, and further may be 2-5wt%; Optionally, the binder is polyvinylidene fluoride, preferably with a molecular weight of 800,000-1.2 million; Optionally, the coating also contains a dispersant, the content of which may be 0.5-3wt%, and further may be 1-3wt%; Optionally, the dispersant is polyvinylpyrrolidone, preferably with a molecular weight of 600,000-1,200,000. 4. according to the described sodium ion secondary battery cathode current collector according to any one of claim 1-3, it is characterized in that, contain nanocellulose, conducting agent, binding agent, dispersion agent in the described coating, optionally , the mass ratio of nanocellulose, conductive agent, binder, and dispersant is (30-75):(10-40):(1-5):(0.5-3). 5. the preparation method of the described sodium ion secondary battery cathode current collector of any one of claim 1-4, is characterized in that, comprises: 1) mixing the nanocellulose, conductive agent, binder, dispersant and solvent according to the proportioning ratio to prepare a slurry with a solid content of 5-50wt%; 2) The slurry is evenly coated on the upper and lower surfaces of the metal foil, and dried; 3) the metal foil coated in step 2) is oxidized under _NO atmosphere; 4) hot rolling the oxidized metal foil in step 3) to obtain a current collector; Optionally, the solid content of the slurry in step 1) is 10-20wt%; and/or, Optionally, step 1) is fully dispersed in Hongyun DL-500L equipment, the linear velocity of the dispersion disc is 10-200m/min, preferably 60-100m/min; the dispersion time is 120-240min; and/or, Optionally, step 2) is coated on a Kejing Zhida Technology MG200 micro-gravure coater; optionally, the coating speed is 2-10m/min, and the drying temperature is 80-130°C; optionally, The coating thickness after drying is 0.5-5 μm, further optionally 1-2 μm; and/or, Optionally, step 3) NO ₂ flow rate is 10L-30L/min, oxidation temperature is 60-120°C; and/or, Optionally, the pressure of step 4) hot rolling is 0.1-2 MPa, and the temperature of hot rolling is 60-80°C. 6. the sodium ion secondary battery cathode current collector prepared by the method described in any one of claims 1-5. 7. The application of the positive electrode current collector of the sodium ion secondary battery described in any one of claims 1-5 in the preparation of the sodium ion secondary battery. 8 . A sodium ion secondary battery positive pole piece, characterized in that it comprises the sodium ion secondary battery positive current collector according to any one of claims 1-5. 9. A sodium ion secondary battery, characterized in that it comprises the positive pole piece of the sodium ion secondary battery according to claim 7; or comprises the positive current collector of the sodium ion secondary battery according to any one of claims 1-5. 10. An equipment for preparing a positive electrode current collector of a sodium ion secondary battery, characterized in that it comprises an unwinding reel connected in sequence; a transfer shaft; a first micro-gravure coater; a first oven; a second micro-gravure coater; Second oven; NO ₂ oxidation equipment; hot pressing roller; winding shaft; optionally, the NO ₂ oxidation equipment is provided with NO ₂ gas outlet and NO ₂ gas inlet.

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