Positive pole piece of sodium-ion battery, sodium-ion battery and preparation equipment of sodium-ion battery

Abstract

The utility model discloses a sodium ion battery positive pole piece, a sodium ion battery and preparation equipment thereof, and relates to the technical field of sodium ion battery preparation, the positive pole piece is composed of a seven-layer structure, the middle layer is an aluminum foil, and the upper and lower surfaces tightly attached to the aluminum foil are aramid fiber functional layers. The positive pole piece provided by the utility model is composed of seven layers, the middle layer is the aluminum foil, the aramid functional layers are tightly attached to the upper surface and the lower surface of the aluminum foil, the organic aluminum functional layer is tightly attached to the aramid functional layers, and the middle layer and the organic aluminum functional layer are used for hindering reaction between NaOH / Na2CO3 on the surface of a sodium ion positive pole material and the aluminum foil and providing conductivity. The sodium ion positive electrode slurry coating layer is tightly attached to the organic aluminum functional layer, so that the reaction of NaOH / Na2CO3 on the surface of the sodium ion positive electrode material and aluminum foil can be effectively inhibited, the belt breakage phenomenon in the rolling process is inhibited, and the problems of overlarge resistance of a positive electrode plate and overlarge resistance of a battery caused by reaction products of NaOH / Na2CO3 and the aluminum foil are also inhibited; the capacity and the cycle life of the sodium-ion battery are effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of sodium ion battery preparation, in particular to a sodium ion battery positive electrode sheet, a sodium ion battery and preparation equipment thereof. Background Art

[0002] In the 21st century, lithium batteries have been used in many fields, but as their usage continues to increase, the problem of lithium resource consumption has become prominent. Production volume is difficult to meet consumption, and the price of lithium is rising. In comparison, sodium has a wide range of sources and abundant reserves. Its reserves are 420 times that of lithium, and its price advantage is obvious. Sodium-ion batteries not only have lower costs, which are 30% to 50% lower than lithium-ion batteries, but also have many advantages, such as abundant resources, low prices, and good safety. This makes sodium-ion batteries show attractive application prospects in energy storage, hybrid power and other fields, and is expected to become an important force in the future battery field and provide strong support for the development of various industries.

[0003] The preparation process of sodium ion battery positive electrode materials requires the addition of excess Na salt to obtain positive electrode materials with good crystallinity. Therefore, there will be a small amount of Na remaining in the sodium ion positive electrode materials (existing in the form of Na2O at high temperatures). After the temperature drops to room temperature, Na2O will adsorb CO2 and H2O in the air to form NaOH and Na2CO3, etc., making the positive electrode material alkaline. The alkalinity of Na is stronger than that of Li, so the alkalinity of sodium ion positive electrode materials is much higher than that of lithium ion positive electrode materials.

[0004] The positive electrode of sodium-ion batteries uses aluminum foil, the current collector used for lithium-ion batteries. The NaOH and Na2CO3 on the surface of the sodium-ion positive electrode material react with the aluminum foil to a certain extent, causing the electrode to break easily during the rolling process, affecting the processing performance of the product. In order to prevent the electrode from breaking, the compaction density of the electrode is reduced, which can slow down the frequency of breakage to a certain extent, but it cannot fundamentally solve the problem of electrode breakage, let alone meet the product capacity design requirements.

[0005] Another consequence of the reaction between NaOH and Na2CO3 on the surface of the sodium-ion positive electrode material and the aluminum foil is that the reaction products cause the electrode sheet to have excessive resistance, which ultimately leads to excessive battery resistance and ultimately a shortened battery cycle life. Therefore, it is necessary to provide a sodium-ion battery positive electrode sheet, a sodium-ion battery, and a manufacturing device thereof to address the problems of the existing technology. Utility Model Content

[0006] The purpose of the utility model is to make up for the deficiencies of the prior art and provide a sodium ion battery positive electrode sheet, a sodium ion battery and a preparation device thereof, which effectively inhibit the reaction of NaOH / Na2CO3 on the surface of the sodium ion positive electrode material with aluminum foil, inhibit the belt breakage phenomenon during the rolling process, and also inhibit the problems of excessive positive electrode sheet resistance and excessive battery resistance caused by the reaction products of NaOH / Na2CO3 and aluminum foil, thereby effectively improving the capacity and cycle life of the sodium ion battery.

[0007] In order to solve the above technical problems, the utility model provides the following technical solutions: a sodium ion battery positive electrode plate, the positive electrode plate is composed of a 7-layer structure, the middle layer is aluminum foil, and the upper and lower surfaces of the aluminum foil are closely attached to the aramid functional layer, the aramid functional layer is composed of aramid raw material and conductive agent, and the organic aluminum functional layer is closely attached to the aramid functional layer. The organic aluminum functional layer is composed of conductive agent, polymer blocker, binder, and dispersant. The sodium ion positive electrode slurry coating layer is closely attached to the organic aluminum functional layer, and the positive electrode slurry is composed of four parts: positive electrode active material, conductive agent, binder, and NMP.

[0008] A sodium ion battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator;

[0009] The positive electrode sheet is composed of aluminum foil, aramid functional layer, organic aluminum functional layer and positive electrode slurry coating layer;

[0010] The negative electrode plate is composed of four parts: a negative electrode active material, a conductive agent, a binder, and a current collector. The negative electrode active material is a hard carbon material. The conductive agent is one of acetylene black, carbon black, carbon nanotubes, and graphene. The binder is CMC and SBR. The current collector is one of copper foil and aluminum foil.

[0011] The diaphragm is one of polyethylene, polypropylene, polyvinylidene fluoride, and aramid;

[0012] The electrolyte consists of an organic solvent and electrolyte sodium salt.

[0013] Furthermore, the organic solvent is one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, fluoroethylene carbonate, ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and methyl tert-butyl ether, and the electrolyte sodium salt is one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, and sodium perchlorate.

[0014] A preparation device for a sodium-ion battery positive electrode sheet, comprising an unwinding shaft, a transfer shaft, an aramid coating area, three micro-gravure coating devices, three drying devices, an organic aluminum functional layer coating area, a slurry coating area, a slurry coating device, and a winding shaft, wherein the organic aluminum functional layer coating area is located between the aramid coating area and the slurry coating area, the three micro-gravure coating devices are respectively located in each coating area, and the three drying devices are respectively located after each coating area.

[0015] Furthermore, the unwinding shaft is used to place aluminum foil to provide raw materials for preparing positive electrode sheets, the transfer shaft is used to transport the aluminum foil on the unwinding shaft to the aramid coating area, the aramid coating area is used to perform coating operations on the aramid functional layer slurry, the micro-gravure coating equipment behind the aramid coating area is used to evenly coat the aramid functional layer slurry on the aluminum foil, the drying equipment behind the aramid coating area is used to dry the aluminum foil after coating the aramid functional layer slurry, so that the aramid functional layer is firmly attached to the aluminum foil, the organic aluminum functional layer coating area is used to perform coating operations on the organic aluminum functional layer slurry, and the micro-gravure coating equipment behind the organic aluminum functional layer coating area is used to evenly coat the organic aluminum functional layer slurry on the composite foil.

[0016] Furthermore, the drying equipment after the organic aluminum functional layer coating area is used to dry the composite foil after coating the organic aluminum functional layer slurry, so that the organic aluminum functional layer is stably formed. The slurry coating area is used to perform the coating operation of the positive electrode slurry. The slurry coating equipment after the slurry coating area is used to coat the positive electrode slurry on the composite foil. The drying equipment after the slurry coating area is used to dry the composite foil after coating the positive electrode slurry to ensure that the positive electrode slurry is dry and solidified. The winding shaft is used to wind up the dried positive electrode sheet to complete the preparation of the positive electrode sheet.

[0017] Compared with the existing technology, the sodium ion battery positive electrode sheet, sodium ion battery and its preparation equipment have the following beneficial effects:

[0018] The positive electrode plate provided by the present invention is composed of a 7-layer structure, wherein the middle layer is aluminum foil, the upper and lower surfaces of the aluminum foil are aramid functional layers, and the organic aluminum functional layer is adjacent to the aramid functional layer. The functions of the two layers are to hinder the reaction between NaOH / Na2CO3 on the surface of the sodium ion positive electrode material and the aluminum foil, and to provide conductivity. The sodium ion positive electrode slurry coating layer is adjacent to the organic aluminum functional layer, which can effectively inhibit the reaction between NaOH / Na2CO3 on the surface of the sodium ion positive electrode material and the aluminum foil, inhibit the belt breakage phenomenon during the rolling process, and also inhibit the problem of excessive positive electrode plate resistance and excessive battery resistance caused by the reaction products of NaOH / Na2CO3 and the aluminum foil, thereby effectively improving the capacity and cycle life of the sodium ion battery.

[0019] Other advantages, objectives and features of the present invention will be described in part in the following description and will be apparent to those skilled in the art based on an examination of the following or may be learned from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0021] Figure 1 This is a schematic structural diagram of a positive electrode sheet for a sodium ion battery;

[0022] Figure 2 Schematic diagram of the structure of a sodium ion battery;

[0023] Figure 3 Schematic diagram of a sodium-ion battery positive electrode sheet preparation device.

[0024] Figure 3 Middle: 1. Unwinding shaft; 2. Transfer shaft; 3. Aramid coating area; 4. Micro-gravure coating equipment; 5. Drying equipment; 6. Organic aluminum functional layer coating area; 7. Slurry coating area; 8. Slurry coating equipment; 9. Rewinding shaft. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below. The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0026] The present invention will be further described below with reference to the embodiments.

[0027] A sodium-ion battery positive electrode plate consists of a 7-layer structure. The middle layer is aluminum foil, which plays a conductive and supporting role. The upper and lower surfaces of the aluminum foil are aramid functional layers. The aramid functional layers are composed of aramid raw materials and conductive agents. The aramid raw materials have excellent mechanical properties and stability, which can enhance the strength and durability of the plate. The addition of the conductive agent improves the conductivity of the aramid functional layer and facilitates the transmission of electrons.

[0028] Close to the aramid functional layer is the organic aluminum functional layer, which is composed of a conductive agent, a polymer blocker, a binder, and a dispersant. The conductive agent ensures good conductivity, and the polymer blocker can effectively prevent the reaction of NaOH and Na2CO3 on the surface of the sodium ion positive electrode material with the aluminum foil, thereby reducing the occurrence of side reactions and extending the service life of the battery.

[0029] Closely attached to the organic aluminum functional layer is the sodium ion positive electrode slurry coating layer. The positive electrode slurry is composed of four parts: positive electrode active material, conductive agent, binder, and NMP. The positive electrode active material is the key factor in determining battery performance. It can realize the embedding and extraction of sodium ions during the charge and discharge process. The conductive agent improves the conductivity of the slurry. The binder ensures the firm bonding of the active material and other components. NMP acts as a solvent to enable the components to be evenly mixed.

[0030] The mass ratio of aramid raw material to conductive agent in the aramid functional layer is 30-95:5-70. This ratio can ensure that the aramid functional layer has good mechanical properties and suitable conductivity.

[0031] The cost ratios of the conductive agent, polymer blocker, binder, and dispersant in the organic aluminum functional layer are 30-55:40-65:1-5:0.1-2. This proportion enables the organic aluminum functional layer to fully exert its role in preventing reactions, providing conductivity, and maintaining structural stability.

[0032] The solid content of the positive electrode slurry in the positive electrode slurry coating layer is controlled between 45-65%. This solid content range can ensure the uniformity and stability of the slurry during the coating process, thereby ensuring the performance of the positive electrode sheet.

[0033] A sodium-ion battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator. The positive electrode sheet is composed of aluminum foil, an aramid functional layer, an organic aluminum functional layer and a positive electrode slurry coating layer. This unique structural design enables the positive electrode sheet to stably achieve the insertion and extraction of sodium ions during the charge and discharge process, while effectively suppressing the occurrence of side reactions, thereby improving the performance and life of the battery.

[0034] The negative electrode sheet is composed of four parts: negative electrode active material, conductive agent, binder, and current collector. The negative electrode active material is a hard carbon material, which has a high sodium storage capacity and good cycle stability. The conductive agent is one of acetylene black, carbon black, carbon nanotubes, and graphene. These conductive agents can improve the conductivity of the negative electrode sheet and promote the transmission of electrons. The binder is CMC and SBR, which can ensure the firm bonding of the negative electrode active material and other components. The current collector is one of copper foil and aluminum foil, which plays a conductive and supporting role.

[0035] The diaphragm is one of polyethylene, polypropylene, polyvinylidene fluoride, and aramid. The function of the diaphragm is to isolate the positive and negative electrodes to prevent short circuits, while allowing sodium ions to pass freely during the charging and discharging process.

[0036] The electrolyte is composed of an organic solvent and an electrolyte sodium salt. The organic solvent is one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, fluoroethylene carbonate, ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and methyl tert-butyl ether. These organic solvents can dissolve the electrolyte sodium salt to form an ion-conductive environment. The electrolyte sodium salt is one of sodium hexafluorophosphate, sodium bis(fluorosulfonylimide), sodium bis(trifluoromethanesulfonylimide), sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, and sodium perchlorate. They can dissociate into sodium ions in the electrolyte and participate in the charge and discharge reactions of the battery.

[0037] A preparation device for a sodium-ion battery positive electrode sheet, comprising an unwinding shaft 1, a transfer shaft 2, an aramid coating area 3, three micro-gravure coating devices 4, three drying devices 5, an organic aluminum functional layer coating area 6, a slurry coating area 7, a slurry coating device 8, and a winding shaft 9. The organic aluminum functional layer coating area 6 is located between the aramid coating area 3 and the slurry coating area 7, the three micro-gravure coating devices 4 are respectively located in each coating area, and the three drying devices 5 are respectively located after each coating area.

[0038] The unwinding shaft 1 is used to place aluminum foil to provide raw materials for preparing positive electrode sheets. The transfer shaft 2 is used to transport the aluminum foil on the unwinding shaft 1 to the aramid coating area 3. The aramid coating area 3 is used to apply the aramid functional layer slurry. The micro-gravure coating equipment 4 behind the aramid coating area 3 is used to evenly apply the aramid functional layer slurry on the aluminum foil. The drying equipment 5 behind the aramid coating area 3 is used to dry the aluminum foil after coating the aramid functional layer slurry so that the aramid functional layer is firmly attached to the aluminum foil. The organic aluminum functional layer coating area 6 is used to apply the organic aluminum functional layer slurry. The micro-gravure coating equipment 4 behind the organic aluminum functional layer coating area 6 is used to evenly apply the organic aluminum functional layer slurry on the composite foil.

[0039] The drying equipment 5 after the organic aluminum functional layer coating area 6 is used to dry the composite foil after coating the organic aluminum functional layer slurry, so that the organic aluminum functional layer is stably formed. The slurry coating area 7 is used to perform the coating operation of the positive electrode slurry. The slurry coating equipment 8 after the slurry coating area 7 is used to coat the positive electrode slurry on the composite foil. The drying equipment 5 after the slurry coating area 7 is used to dry the composite foil after coating the positive electrode slurry to ensure that the positive electrode slurry is dry and solidified. The winding shaft 9 is used to wind up the dried positive electrode sheet to complete the preparation of the positive electrode sheet.

[0040] The working process of the preparation equipment is as follows: first, the aluminum foil is placed on the unwinding shaft 1, and the aluminum foil is transported to the aramid coating area 3 through the transfer shaft 2. In the aramid coating area 3, the micro-gravure coating device 4 coats the aramid functional layer slurry on the aluminum foil to form a composite foil. The coated composite foil enters the drying device 5 for drying, so that the aramid functional layer is firmly attached to the aluminum foil. The dried composite foil is transported to the organic aluminum functional layer coating area 6, in which the micro-gravure coating device 4 coats the organic aluminum functional layer slurry on the composite foil. The composite foil after the aluminum functional layer slurry enters the drying equipment 5 for drying, so that the organic aluminum functional layer is stably formed. Subsequently, the composite foil enters the slurry coating area 7. In the slurry coating area 7, the slurry coating equipment 8 coats the positive electrode slurry on the composite foil. The composite foil after coating the positive electrode slurry enters the drying equipment 5 for drying to ensure that the positive electrode slurry is dry and solidified. Finally, the dried positive electrode sheet is wound by the winding shaft 9 to complete the entire preparation process. Through the above work flow, the preparation equipment can efficiently and stably prepare sodium ion battery positive electrode sheets.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A sodium ion battery positive electrode plate, characterized in that: The positive electrode plate is composed of a 7-layer structure, the middle layer is aluminum foil, and the upper and lower surfaces of the aluminum foil are aramid functional layers, the aramid functional layers are composed of aramid raw materials and conductive agents, and the organic aluminum functional layer is closely attached to the aramid functional layer. The organic aluminum functional layer is composed of a conductive agent, a polymer blocker, a binder, and a dispersant. The sodium ion positive electrode slurry coating layer is closely attached to the organic aluminum functional layer, and the positive electrode slurry is composed of four parts: positive electrode active material, conductive agent, binder, and NMP.

2. A sodium ion battery, characterized in that: Including positive electrode sheet, negative electrode sheet, electrolyte and diaphragm; The positive electrode sheet is composed of aluminum foil, aramid functional layer, organic aluminum functional layer and positive electrode slurry coating layer; The negative electrode sheet is composed of four parts: negative electrode active material, conductive agent, binder and current collector; The diaphragm is one of polyethylene, polypropylene, polyvinylidene fluoride, and aramid; The electrolyte consists of an organic solvent and electrolyte sodium salt.

3. A sodium ion battery according to claim 2, characterized in that: The negative electrode active material is a hard carbon material, the conductive agent is one of acetylene black, carbon black, carbon nanotubes, and graphene, the binder is CMC and SBR, and the current collector is one of copper foil and aluminum foil.

4. A sodium ion battery according to claim 2, characterized in that: The organic solvent is one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, propylene carbonate, methyl acetate, ethyl propionate, fluoroethylene carbonate, ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and methyl tert-butyl ether; the electrolyte sodium salt is one of sodium hexafluorophosphate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium trifluoromethanesulfonate, sodium tetrafluoroborate, sodium difluorophosphate, and sodium perchlorate.

5. A sodium ion battery positive electrode sheet preparation device, characterized in that: The preparation equipment comprises an unwinding shaft (1), a transfer shaft (2), an aramid coating area (3), three micro-gravure coating devices (4), three drying devices (5), an organic aluminum functional layer coating area (6), a slurry coating area (7), a slurry coating device (8) and a winding shaft (9), wherein the organic aluminum functional layer coating area (6) is located between the aramid coating area (3) and the slurry coating area (7), the three micro-gravure coating devices (4) are respectively located in each coating area, and the three drying devices (5) are respectively located after each coating area.

6. The equipment for preparing a positive electrode sheet for a sodium ion battery according to claim 5, characterized in that: The unwinding shaft (1) is used to place aluminum foil to provide raw materials for preparing positive electrode sheets. The transfer shaft (2) is used to transport the aluminum foil on the unwinding shaft (1) to the aramid coating area (3). The aramid coating area (3) is used to apply the aramid functional layer slurry. The micro-gravure coating device (4) behind the aramid coating area (3) is used to evenly apply the aramid functional layer slurry on the aluminum foil. The drying device (5) behind the aramid coating area (3) is used to dry the aluminum foil after being coated with the aramid functional layer slurry so that the aramid functional layer is firmly attached to the aluminum foil. The organic aluminum functional layer coating area (6) is used to apply the organic aluminum functional layer slurry. The micro-gravure coating device (4) behind the organic aluminum functional layer coating area (6) is used to evenly apply the organic aluminum functional layer slurry on the composite foil.

7. The equipment for preparing a positive electrode sheet for a sodium ion battery according to claim 5, characterized in that: The drying device (5) after the organic aluminum functional layer coating area (6) is used to dry the composite foil after the organic aluminum functional layer slurry is coated, so that the organic aluminum functional layer is stably formed. The slurry coating area (7) is used to perform the coating operation of the positive electrode slurry. The slurry coating device (8) after the slurry coating area (7) is used to coat the positive electrode slurry on the composite foil. The drying device (5) after the slurry coating area (7) is used to dry the composite foil after the positive electrode slurry is coated, ensuring that the positive electrode slurry is dried and solidified. The winding shaft (9) is used to wind up the dried positive electrode sheet to complete the preparation of the positive electrode sheet.

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