A sodium ion battery sodium replenishing device and a sodium ion battery sodium replenishing method

Abstract

The present invention provides a sodium replenishing device for sodium ion batteries and a sodium replenishing method for sodium ion batteries, belonging to the field of sodium replenishing for sodium ion batteries. The present invention provides a sodium replenishing device for sodium ion batteries, the sodium replenishing device for sodium ion batteries comprises a pole piece sodium replenishing device, a circulating hot air system and a roller device; the circulating hot air system is located on both sides of the roller device; the pole piece sodium replenishing device is located on the other side of the circulating hot air system. The results of the embodiment show that the sodium replenishing pole piece with a protective layer obtained by the device provided by the present invention can effectively improve the sodium ion loss caused by the SEI film during the first charging of the sodium ion battery and reduce the occurrence and formation of side reactions. For assembled sodium ion cells, the first charge and discharge efficiency can be increased by 3% to 10% compared with the non-sodium replenished cells, and the cycle is >200 weeks compared with the conventional sodium ion cells.

Description

Technical Field

[0001] The invention relates to the field of sodium replenishment of sodium ion batteries, and in particular to a sodium replenishment device for sodium ion batteries and a sodium replenishment method for sodium ion batteries. Background Art

[0002] Recently, due to the rapid development of electric vehicles and renewable energy technologies, the market demand for lithium-ion batteries has continued to rise, which has also led to an increase in the price of lithium raw materials. At present, China relies heavily on imports from the international market for lithium resources. At the same time, China is facing increasing pressure on energy resources, and relying solely on lithium-ion battery technology is not enough to completely transform the existing energy consumption pattern.

[0003] Sodium and lithium are both elements of the alkali metal family and have similar chemical properties. Compared with lithium, sodium has significant advantages in resource abundance and cost control. In addition, sodium-ion batteries also have fast charging and discharging capabilities, excellent low-temperature performance, good safety characteristics, and a similar production and manufacturing process to lithium-ion batteries. These characteristics make sodium-ion batteries a potential alternative technology that is expected to develop into the next generation of commercial energy storage solutions.

[0004] However, compared with lithium-ion batteries, sodium-ion batteries still face challenges in first-cycle coulombic efficiency, cycle stability and energy density. Therefore, developing effective sodium replenishment technology is of great significance to improving the performance of sodium-ion batteries.

[0005] The invention patent with application number 202211615410.8 discloses a method, device and sodium ion battery for cold spraying of negative electrode sheets to replenish sodium. During the sodium replenishment process, the sodium powder is accelerated through the air cavity to form a sodium powder jet, which passes through the film coil and is sprayed onto the electrode coil at a high speed. The coated sodium sheet is embedded in the pores of the electrode sheet to obtain the electrode sheet after sodium replenishment. Since the sodium powder is coated by the film coil during the spraying process, it is highly safe. The film coating material will dissolve in the electrolyte or react with the electrolyte to form a gel after injection, thereby releasing the coated sodium powder. However, this method of sodium replenishment requires the consumption of film coils, which increases the production cost. After the coating material dissolves in the electrolyte or reacts with the electrolyte, it will have a certain effect on the conductivity of the electrolyte, thereby affecting the electrical properties of the battery. On the other hand, the stability of the sodium layer after sodium replenishment is poor, and the battery's first cycle coulomb efficiency, energy density and cycle stability still cannot meet the technical requirements.

[0006] Therefore, how to further improve the stability of the sodium replenishment layer, thereby improving the first cycle coulombic efficiency, energy density and cycle stability of the battery, has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0007] The object of the present invention is to provide a sodium-replenishing device for a sodium-ion battery and a sodium-replenishing method for a sodium-ion battery. The sodium layer formed after the sodium-replenishing device for a sodium-ion battery provided by the present invention replenishes sodium can improve the first cycle coulombic efficiency, energy density and cycle stability of the sodium-ion battery, and extend the service life of the sodium-ion battery, thereby meeting the needs of electric vehicles, energy storage systems and other fields for high-performance and long-life batteries.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a sodium-ion battery sodium-supplementing device, characterized in that the sodium-ion battery sodium-supplementing device comprises a pole piece sodium-supplementing device, a circulating hot air system and a roller device;

[0010] The circulating hot air system is located on both sides of the roller device;

[0011] The electrode sodium supplement device is located on the other side of the circulating hot air system.

[0012] Preferably, the sodium-ion battery sodium replenishing device comprises an inert gas chamber, and the pole piece sodium replenishing device, circulating hot air system and roller device are located inside the inert gas chamber.

[0013] Preferably, the electrode sodium supplement device comprises a liquefaction tank, molten metal sodium and a coating device, the molten metal sodium is located inside the liquefaction tank, and the coating device is located below the liquefaction tank.

[0014] Preferably, a roller assembly is further provided between the pole piece sodium supplement device and the circulating hot air system.

[0015] Preferably, the sodium-ion battery sodium replenishing device further comprises a pole piece unwinding assembly and a pole piece winding assembly, the pole piece unwinding assembly is located at the starting position of the sodium-ion battery sodium replenishing device, and the pole piece winding assembly is located at the end position of the sodium-ion battery sodium replenishing device.

[0016] The present invention provides a method for replenishing sodium in a sodium ion battery, and the sodium ion battery is replenished with sodium using the sodium ion battery replenishing device described in the technical solution.

[0017] Preferably, the method for replenishing sodium in a sodium ion battery comprises the following steps:

[0018] (1) filling an inert gas into a sodium ion battery sodium replenishing device, then adding metallic sodium into a pole piece sodium replenishing device in the sodium ion battery sodium replenishing device, and then heating to obtain molten metallic sodium;

[0019] (2) coating the molten metal sodium obtained in step (1) on the electrode to obtain a sodium-supplemented electrode;

[0020] (3) The sodium-supplemented electrode obtained in step (2) is first subjected to a first replacement reaction by a circulating hot air system, then pressed by a roller device, and finally subjected to a second replacement reaction by a circulating hot air system to obtain a sodium-supplemented electrode containing a protective layer.

[0021] Preferably, the thickness of the metal sodium supplement layer in the electrode after sodium supplementation obtained in step (2) is ≤10 μm.

[0022] Preferably, the atmosphere of the circulating hot air system in step (3) is carbon dioxide; the mass concentration of the carbon dioxide is >98%; and the flow rate of the carbon dioxide is ≤50 L / min.

[0023] Preferably, the protective layer of the sodium-replenishing electrode obtained in step (3) is composed of carbon, sodium oxide and sodium carbonate.

[0024] The present invention provides a sodium-ion battery sodium-replenishing device, characterized in that the sodium-ion battery sodium-replenishing device comprises a pole piece sodium-replenishing device, a circulating hot air system and a roller device; the circulating hot air system is located on both sides of the roller device; and the pole piece sodium-replenishing device is located on the other side of the circulating hot air system. The sodium-ion battery sodium-replenishing device provided by the present invention first coats molten metal sodium on the pole piece through the pole piece sodium-replenishing device to form a metal sodium-replenishing layer, and then passes the pole piece through the circulating hot air system, and a replacement reaction occurs under the action of carbon dioxide in the circulating hot air system, thereby forming a protective layer on the upper surface of the metal sodium-replenishing layer, and then passes through the roller device for pressing, and then passes through the circulating hot air system for a second replacement reaction, so as to ensure that the pole piece surface is evenly covered by the protective layer, forming a protective layer composed of carbon, sodium oxide and sodium carbonate, improving the sodium ion loss caused by the SEI film during the first charging process, reducing the occurrence of side reactions, thereby improving the first cycle coulomb efficiency, energy density and cycle stability of the sodium ion battery, and extending the service life of the sodium ion battery. The results of the embodiments show that the sodium-supplemented electrode with a protective layer obtained by the device provided by the present invention can effectively improve the sodium ion loss caused by the SEI film during the first charging of the sodium ion battery and reduce the occurrence of side reactions. For the assembled sodium ion battery cells, the first charge and discharge efficiency can be increased by 3% to 10% compared with the non-sodium-supplemented battery cells, and the cycle is >200 weeks compared with the conventional sodium ion battery cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of the sodium ion battery sodium replenishing device provided by the present invention;

[0026] Figure 1 In the figure, 1 is a pole piece unwinding assembly, 2 is a roller assembly, 3 is a liquefaction tank, 4 is molten metal sodium, 5 is a roller device, 6 is a pole piece winding assembly, 7 is a pole piece, 8 is a coating device, 9 is a circulating hot air system, and 14 is an inert gas chamber;

[0027] Figure 2 This is a schematic diagram of the structure of the sodium ion battery provided by the present invention after sodium supplementation;

[0028] Figure 2 In the figure, 10 is an active material layer, 11 is a metal sodium supplement layer, 12 is a protective layer, and 13 is a foil material. DETAILED DESCRIPTION

[0029] The present invention provides a sodium-ion battery sodium-replenishing device, which includes a pole piece sodium-replenishing device, a circulating hot air system and a roller device. In one embodiment of the present invention, the circulating hot air system is located on both sides of the roller device. In one embodiment of the present invention, the pole piece sodium-replenishing device is located on the other side of the circulating hot air system. The present invention provides a pole piece sodium-replenishing device, a circulating hot air system and a roller device. When the pole piece passes through the pole piece sodium-replenishing device, molten metal sodium can be coated on the upper surface of the pole piece. Then, the pole piece after sodium-replenishing first passes through the circulating hot air system on one side of the roller device. In this process, a replacement reaction (4Na+3CO2→2Na2O+C and Na2O+CO2→Na2CO3) occurs, thereby forming a protective layer on the upper surface of the metal sodium-replenishing layer, and then passes through the roller device for pressing, and then passes through the circulating hot air system on the other side of the roller device to perform a second replacement reaction to ensure that the pole piece surface is evenly covered by the protective layer. The device provided by the present invention can form a protective layer on the surface of the sodium replenishment layer, thereby extending the service life of the sodium ion battery, improving the battery's first cycle coulombic efficiency, energy density and cycle stability, thereby meeting the needs of electric vehicles, energy storage systems and other fields for high-performance, long-life batteries.

[0030] In one embodiment of the present invention, the electrode sodium supplement device comprises a liquefaction tank, molten metal sodium and a coating device. In one embodiment of the present invention, the molten metal sodium is located inside the liquefaction tank, and the coating device is located below the liquefaction tank.

[0031] like Figure 1 As shown, in one embodiment of the present invention, the sodium ion battery sodium replenishing device includes a pole piece unwinding assembly 1, a roller assembly 2, a liquefaction tank 3, molten metal sodium 4, a roller device 5, a pole piece winding assembly 6, a pole piece 7, a coating device 8, a circulating hot air system 9 and an inert gas chamber 14.

[0032] In one embodiment of the present invention, the pole piece unwinding assembly 1 is located at the starting position of the sodium ion battery sodium replenishing device, and the pole piece winding assembly 6 is located at the end position of the sodium ion battery sodium replenishing device.

[0033] In one embodiment of the present invention, the sodium-ion battery sodium replenishing device comprises, from left to right, a pole piece unwinding assembly 1, a roller assembly 2, a coating device 8, a circulating hot air system 9, a roller device 5, a circulating hot air system 9 and a pole piece winding assembly 6.

[0034] In one embodiment of the present invention, the pole piece 7 in the sodium ion battery sodium replenishing device contacts the upper surface of the unwinding assembly 1, the upper surface of the roller assembly 2, the bottom of the coating device 8 and the upper surface of the pole piece winding assembly 6 in sequence.

[0035] In one embodiment of the present invention, the pole piece 7 in the sodium ion battery sodium replenishing device sequentially passes through the circulating hot air system 9 on both sides of the roller device 5.

[0036] In one embodiment of the present invention, the sodium-ion battery sodium replenishing device includes an inert gas chamber 14. In the present invention, the pole piece unwinding assembly 1, the roller assembly 2, the liquefaction tank 3, the molten metal sodium 4, the counter-roller device 5, the pole piece winding assembly 6, the pole piece 7, the coating device 8 and the circulating hot air system 9 are located inside the inert gas chamber. The present invention has no special restrictions on the shape and size of the inert gas chamber, and it is sufficient that the pole piece sodium replenishing device, the circulating hot air system and the counter-roller device are completely located inside the inert gas chamber. In one embodiment of the present invention, the shape of the inert gas chamber is preferably a rectangular parallelepiped. In the present invention, the inert gas chamber can make the interior of the device in an inert gas atmosphere, thereby avoiding oxidation reactions such as oxidation of the molten metal sodium during the sodium replenishing process.

[0037] In the present invention, the inert gas in the inert gas chamber 14 preferably includes any one or two of helium, neon, argon, krypton and xenon. By using the above inert gas, the present invention can avoid oxidation and other reactions of the molten metal sodium during the sodium supplementation process.

[0038] In one embodiment of the present invention, the inert gas in the inert gas chamber 14 may be helium or argon. The present invention uses the above inert gas at a lower cost.

[0039] In the sodium ion battery sodium replenishing device provided by the present invention, in the inert atmosphere provided by the inert gas chamber 14, the pole piece 7 is released from the pole piece unwinding assembly 1, and after passing through the roller assembly 2, the molten metal sodium 4 in the liquefaction pool 3 is coated on the upper surface of the pole piece 7 by the coating device 8, and then the pole piece 7 first passes through the circulating hot air system 9 on the left side, and a replacement reaction occurs under the action of carbon dioxide in the circulating hot air system 9, thereby forming a protective layer on the upper surface of the metal sodium replenishing layer of the pole piece 7, and then passes through the roller device 5 for pressing, and then passes through the circulating hot air system 9 on the right side of the roller device 5, and a second replacement reaction is performed to ensure that the pole piece surface is evenly covered by the protective layer, forming a protective layer composed of carbon, sodium oxide and sodium carbonate, improving the sodium ion loss caused by the SEI film during the first charging process, reducing the occurrence of side reactions, thereby improving the first cycle coulomb efficiency, energy density and cycle stability of the sodium ion battery, and extending the service life of the sodium ion battery, and then the pole piece 7 after sodium replenishment is wound through the pole piece winding assembly 6.

[0040] The present invention also provides a method for replenishing sodium in a sodium ion battery, and the sodium ion battery is replenished with sodium using the sodium ion battery replenishing device described in the above technical solution.

[0041] The sodium ion battery sodium supplementation method provided by the present invention preferably comprises the following steps:

[0042] (1) filling an inert gas into a sodium ion battery sodium replenishing device, then adding metallic sodium into a pole piece sodium replenishing device in the sodium ion battery sodium replenishing device, and then heating to obtain molten metallic sodium;

[0043] (2) coating the molten metal sodium obtained in step (1) on the electrode to obtain a sodium-supplemented electrode;

[0044] (3) The sodium-supplemented electrode obtained in step (2) is first subjected to a first replacement reaction by a circulating hot air system, then pressed by a roller device, and finally subjected to a second replacement reaction by a circulating hot air system to obtain a sodium-supplemented electrode containing a protective layer.

[0045] The present invention preferably fills the sodium ion battery sodium replenishing device with inert gas, then adds metallic sodium to the pole piece sodium replenishing device in the sodium ion battery sodium replenishing device, and then heats to obtain molten metallic sodium.

[0046] In the present invention, the inert gas preferably includes any one or two of helium, neon, argon, krypton and xenon. The present invention has no special limitation on the pressure of the inert gas, as long as it can ensure that other gases in the device are completely discharged. By using the above-mentioned inert gas, the present invention can avoid oxidation and other reactions of molten metal sodium during the sodium supplementation process.

[0047] In one embodiment of the present invention, the inert gas may be helium or argon. The present invention uses the inert gas at a lower cost.

[0048] In the present invention, the sodium metal preferably includes one or more of sodium block, sodium powder and sodium belt. In one embodiment of the present invention, the sodium metal can be a sodium block, sodium powder or sodium belt. The present invention has no special limitation on the amount of the sodium metal, which can be determined according to the technical common sense of those skilled in the art, as long as the thickness of the sodium layer after correction meets the requirements.

[0049] In the present invention, the heating temperature is preferably 0-200° C., more preferably 100-180° C., and further preferably 100-150° C. The present invention can ensure that the metallic sodium is completely melted by controlling the heating temperature.

[0050] After obtaining the molten metallic sodium, the present invention preferably coats the molten metallic sodium on the pole piece to obtain the sodium-supplemented pole piece.

[0051] In the present invention, the coating method is preferably extrusion coating or spray coating; the coating temperature is preferably 0-200° C., more preferably 100-180° C., and further preferably 100-150° C. The present invention avoids cooling of molten metal sodium by controlling the coating temperature.

[0052] In the present invention, the transmission speed of the electrode during coating is preferably ≤20 m / min. The present invention can ensure that a sodium supplement layer with a thickness that meets the requirements is obtained by controlling the transmission speed of the electrode.

[0053] In one embodiment of the present invention, the transmission speed of the electrode during coating can be 0.5m / min, 1m / min, 2m / min, 5m / min, 8m / min, 10m / min, 12m / min, 15m / min, 18m / min or 20m / min.

[0054] In the present invention, the thickness of the metal sodium supplement layer in the electrode after sodium supplementation is preferably ≤10 μm. The present invention can ensure excellent performance of the battery in terms of cycle coulomb efficiency, energy density and cycle stability by controlling the thickness of the metal sodium supplement layer.

[0055] In one embodiment of the present invention, the thickness of the metal sodium supplement layer in the electrode after sodium supplementation can be 0.1μm, 0.2μm, 0.5μm, 1μm, 1.5μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0056] After obtaining the sodium-supplemented electrode, the present invention preferably first passes the sodium-supplemented electrode through a circulating hot air system for a first replacement reaction, then passes through a roller device for pressing, and finally passes through a circulating hot air system for a second replacement reaction to obtain a sodium-supplemented electrode containing a protective layer.

[0057] In the present invention, the temperature of the circulating hot air system and the roller device is preferably independently 0-200° C., more preferably 100-180° C., and further preferably 100-150° C. The present invention avoids cooling of the molten metal sodium by controlling the temperature of the circulating hot air system and the roller device, thereby facilitating the substitution reaction and pressing thereof.

[0058] In the present invention, the atmosphere of the circulating hot air system is preferably carbon dioxide; the mass concentration of the carbon dioxide is preferably >98%; and the flow rate of the carbon dioxide is preferably ≤50 L / min.

[0059] In one embodiment of the present invention, the flow rate of carbon dioxide can be 0.1L / min, 0.5L / min, 1L / min, 2L / min, 5L / min, 10L / min, 15L / min, 20L / min, 25L / min, 30L / min, 35L / min, 40L / min, 45L / min or 50L / min.

[0060] In the present invention, the reaction equations of the first replacement reaction and the second replacement reaction are: 4Na+3CO2→2Na2O+C and Na2O+CO2→Na2CO3. The present invention can form a protective layer composed of carbon, sodium oxide and sodium carbonate on the surface of the sodium supplement layer through the first replacement reaction and the second replacement reaction, which can effectively improve the sodium ion loss caused by the SEI film during the first charging process and reduce the occurrence of side reactions, thereby improving the first cycle coulomb efficiency, energy density and cycle stability of the sodium ion battery and extending the service life of the sodium ion battery.

[0061] In the present invention, the transmission speed of the electrode after sodium supplementation through the circulating hot air system and the roller device is preferably ≤20m / min. The present invention can ensure the formation of a protective layer on the surface of the sodium supplementation layer by controlling the transmission speed of the electrode.

[0062] In one embodiment of the present invention, the transmission speed of the electrode after sodium supplementation through the circulating hot air system and the roller device can be 0.5m / min, 1m / min, 2m / min, 5m / min, 8m / min, 10m / min, 12m / min, 15m / min, 18m / min or 20m / min.

[0063] After obtaining the sodium-supplementing electrode sheet containing a protective layer, the present invention preferably sequentially subjects the sodium-supplementing electrode sheet containing a protective layer to the steps of sheet making, assembly, formation and capacity division to prepare a sodium-supplementing sodium-ion battery cell containing a protective layer.

[0064] The present invention has no particular limitation on the specific operations of the tableting, assembling, chemical formation and volume separation steps, and the operations of the tableting, assembling, chemical formation and volume separation steps well known to those skilled in the art may be adopted.

[0065] The schematic diagram of the structure of the sodium ion battery after sodium supplementation provided by the present invention is as follows Figure 2 As shown, Figure 2 In the figure, 10 is an active material layer, 11 is a metal sodium supplement layer, 12 is a protective layer, and 13 is a foil. Figure 2 It can be seen that a metal sodium supplement layer is first formed on the active material layer by coating, and then a protective layer is formed on the metal sodium supplement layer.

[0066] The present invention has no particular limitation on the specific materials of the foil and the active material layer, and any foil and active material layer well known to those skilled in the art may be used.

[0067] In the present invention, the thickness of the metal sodium supplement layer is preferably ≤10 μm. The present invention can ensure excellent performance of the battery in terms of cycle coulombic efficiency, energy density and cycle stability by controlling the thickness of the metal sodium supplement layer.

[0068] In one embodiment of the present invention, the thickness of the metal sodium supplement layer in the electrode after sodium supplementation can be 0.1μm, 0.2μm, 0.5μm, 1μm, 1.5μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0069] In the present invention, the protective layer is preferably composed of carbon, sodium oxide and sodium carbonate.

[0070] The sodium replenishment method for a sodium ion battery provided by the present invention replenishes sodium on the surface of an electrode in advance and forms a carbon protective layer and a partial SEI film (Na2O and Na2CO3), which can effectively improve the sodium ion loss caused by the SEI film during the first charging of the sodium ion battery and reduce the occurrence of side reactions, thereby improving the first cycle coulombic efficiency, energy density and cycle stability of the sodium ion battery, extending the service life of the sodium ion battery, thereby meeting the needs of electric vehicles, energy storage systems and other fields for high-performance and long-life batteries.

[0071] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] Example 1

[0073] A sodium-ion battery sodium supplement device comprises a pole piece sodium supplement device, a circulating hot air system and a roller device.

[0074] Example 2

[0075] like Figure 1 The sodium ion battery sodium replenishing device shown includes a pole piece unwinding assembly 1, a roller assembly 2, a liquefaction tank 3, molten metal sodium 4, a counter-roller device 5, a pole piece winding assembly 6, a pole piece 7, a coating device 8, a circulating hot air system 9 and an inert gas chamber 14;

[0076] The sodium ion battery sodium supplementation device comprises, from left to right, a pole piece unwinding assembly 1, a roller assembly 2, a coating device 8, a circulating hot air system 9, a roller device 5, a circulating hot air system 9 and a pole piece winding assembly 6;

[0077] The pole piece 7 in the sodium ion battery sodium supplementation device is in contact with the upper surface of the unwinding assembly 1, the upper surface of the roller assembly 2, the bottom of the coating device 8 and the upper surface of the pole piece winding assembly 6 in sequence;

[0078] The pole piece 7 in the sodium ion battery sodium supplementation device sequentially passes through the circulating hot air system 9 on both sides of the roller device 5;

[0079] The pole piece unwinding assembly 1 , the roller assembly 2 , the liquefaction tank 3 , the molten metal sodium 4 , the roller device 5 , the pole piece winding assembly 6 , the pole piece 7 , the coating device 8 and the circulating hot air system 9 are located inside the inert gas chamber 14 .

[0080] Example 3

[0081] A method for replenishing sodium in a sodium ion battery, using the sodium ion battery replenishing device described in Example 2 to replenish sodium in a sodium ion battery, comprising the following steps:

[0082] (1) filling argon gas into an inert gas chamber in a sodium ion battery sodium replenishing device, then adding sodium powder into a liquefaction pool in the sodium ion battery sodium replenishing device, and then heating at 100° C. to obtain molten metallic sodium;

[0083] (2) coating the molten metal sodium obtained in step (1) on the electrode through a coating device to obtain a sodium-supplemented electrode; the coating method is extrusion coating; the coating temperature is 100° C.; the transmission speed of the electrode during the coating is 5 m / min; the thickness of the metal sodium-supplemented layer in the electrode after sodium supplementation is 5 μm;

[0084] (3) The sodium-supplemented electrode obtained in step (2) is first subjected to a first replacement reaction by a circulating hot air system, then pressed by a roller device, and finally subjected to a second replacement reaction by a circulating hot air system to obtain a sodium-supplemented electrode containing a protective layer; the temperature of the circulating hot air system is 100° C.; the temperature of the roller device is 25° C.; the atmosphere of the circulating hot air system is carbon dioxide; the mass concentration of carbon dioxide is greater than 98%; the flow rate of carbon dioxide is 25 L / min; the reaction equations of the first replacement reaction and the second replacement reaction are: 4Na+3CO2→2Na2O+C and Na2O+CO2→Na2CO3; the transmission speed of the sodium-supplemented electrode through the circulating hot air system and the roller device is 5 m / min.

[0085] Example 4

[0086] A method for replenishing sodium in a sodium ion battery, using the sodium ion battery replenishing device described in Example 2 to replenish sodium in a sodium ion battery, comprising the following steps:

[0087] (1) filling an inert gas chamber in a sodium ion battery sodium replenishing device with argon gas, then adding sodium powder into a liquefaction pool in the sodium ion battery sodium replenishing device, and then heating the liquefaction pool to 150° C. to obtain molten metallic sodium;

[0088] (2) coating the molten metal sodium obtained in step (1) on the electrode through a coating device to obtain a sodium-supplemented electrode; the coating method is extrusion coating; the coating temperature is 150° C.; the transmission speed of the electrode during the coating is 8 m / min; the thickness of the metal sodium-supplemented layer in the electrode after sodium supplementation is 6 μm;

[0089] (3) The sodium-supplemented electrode obtained in step (2) is first subjected to a first replacement reaction by a circulating hot air system, then pressed by a roller device, and finally subjected to a second replacement reaction by a circulating hot air system to obtain a sodium-supplemented electrode containing a protective layer; the temperature of the circulating hot air system is 60° C.; the temperature of the roller device is 25° C.; the atmosphere of the circulating hot air system is carbon dioxide; the mass concentration of carbon dioxide is greater than 99%; the flow rate of carbon dioxide is 40 L / min; the reaction equations of the first replacement reaction and the second replacement reaction are: 4Na+3CO2→2Na2O+C and Na2O+CO2→Na2CO3; the transmission speed of the sodium-supplemented electrode through the circulating hot air system and the roller device is 8 m / min.

[0090] Example 5

[0091] A method for replenishing sodium in a sodium ion battery, using the sodium ion battery replenishing device described in Example 2 to replenish sodium in a sodium ion battery, comprising the following steps:

[0092] (1) filling an inert gas chamber in a sodium ion battery sodium replenishing device with argon gas, then adding sodium powder into a liquefaction pool in the sodium ion battery sodium replenishing device, and then heating the liquefaction pool to 150° C. to obtain molten metallic sodium;

[0093] (2) coating the molten metal sodium obtained in step (1) on the electrode through a coating device to obtain a sodium-supplemented electrode; the coating method is extrusion coating; the coating temperature is 150° C.; the transmission speed of the electrode during the coating is 3 m / min; the thickness of the metal sodium-supplemented layer in the electrode after sodium supplementation is 6 μm;

[0094] (3) The sodium-supplemented electrode obtained in step (2) is first subjected to a first replacement reaction by a circulating hot air system, then pressed by a roller device, and finally subjected to a second replacement reaction by a circulating hot air system to obtain a sodium-supplemented electrode containing a protective layer; the temperature of the circulating hot air system is 25° C.; the temperature of the roller device is 50° C.; the atmosphere of the circulating hot air system is carbon dioxide; the mass concentration of carbon dioxide is greater than 99%; the flow rate of carbon dioxide is 50 L / min; the reaction equations of the first replacement reaction and the second replacement reaction are: 4Na+3CO2→2Na2O+C and Na2O+CO2→Na2CO3; the transmission speed of the sodium-supplemented electrode through the circulating hot air system and the roller device is 3 m / min.

[0095] Comparative Example 1

[0096] The electrode used in Example 3 was not subjected to sodium supplementation and subsequent treatment.

[0097] The sodium-supplementing electrode sheets containing protective layers obtained in Examples 3 to 5 were observed. The sodium-supplementing electrode sheets had uniform thickness and a flat interface. A carbon protective layer and a partial SEI film layer (Na2O and Na2CO3) could be observed on the surface.

[0098] The sodium-supplementing electrodes containing protective layers obtained in Examples 3 to 5 and the electrodes provided in Comparative Example 1 were respectively assembled into sodium-ion batteries, and the performance of the assembled sodium-ion batteries was compared. The results are shown in Table 1:

[0099] Table 1 Performance of sodium ion batteries assembled with the sodium supplementing electrodes containing protective layers obtained in Examples 3 to 5 and the electrodes provided in Comparative Example 1

[0100]

[0101] It can be seen from Table 1 that the sodium-supplemented electrode with a protective layer can effectively improve the sodium ion loss caused by the SEI film during the first charging of the sodium-ion battery and reduce the occurrence and formation of side reactions. For the assembled sodium-ion battery, its first charge and discharge efficiency can be increased by 3%~10% compared with the battery without sodium supplementation, and the cycle is >200 weeks compared with the conventional sodium-ion battery.

[0102] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for replenishing sodium in a sodium ion battery, characterized in that: The sodium ion battery sodium replenishment device is used to replenish sodium for the sodium ion battery, comprising the following steps: (1) filling an inert gas into a sodium ion battery sodium replenishing device, then adding metallic sodium into a pole piece sodium replenishing device in the sodium ion battery sodium replenishing device, and then heating to obtain molten metallic sodium; (2) coating the molten metal sodium obtained in step (1) on the electrode to obtain a sodium-supplemented electrode; (3) The sodium-supplemented electrode obtained in step (2) is first subjected to a first replacement reaction by a circulating hot air system, then subjected to pressing by a roller device, and finally subjected to a second replacement reaction by a circulating hot air system to obtain a sodium-supplemented electrode containing a protective layer; The atmosphere of the circulating hot air system in step (3) is carbon dioxide; the mass concentration of the carbon dioxide is >98%; the flow rate of the carbon dioxide is ≤50L / min; the temperature of the circulating hot air system and the roller device are independently 100-180°C.

2. The method for replenishing sodium in a sodium ion battery according to claim 1, characterized in that: The thickness of the metal sodium supplement layer in the electrode after sodium supplementation obtained in step (2) is ≤10 μm.

3. The method for replenishing sodium in a sodium ion battery according to claim 1, characterized in that: The sodium-replenishing electrode containing a protective layer obtained in step (3) comprises carbon, sodium oxide and sodium carbonate as the protective layer.

4. The method for replenishing sodium in a sodium ion battery according to claim 1, characterized in that: The sodium ion battery sodium supplement device comprises a pole piece sodium supplement device, a circulating hot air system and a roller device; the circulating hot air system is located on both sides of the roller device; the pole piece sodium supplement device is located on the other side of the circulating hot air system; The atmosphere of the circulating hot air system is carbon dioxide; the mass concentration of the carbon dioxide is >98%; the flow rate of the carbon dioxide is ≤50L / min; the temperatures of the circulating hot air system and the roller device are independently 100~180℃.

5. The method for replenishing sodium in a sodium ion battery according to claim 4, characterized in that: The sodium ion battery sodium supplement device comprises an inert gas chamber, and the pole piece sodium supplement device, the circulating hot air system and the roller device are located inside the inert gas chamber.

6. The method for replenishing sodium in a sodium ion battery according to claim 4, characterized in that: The electrode sodium supplement device comprises a liquefaction tank, molten metal sodium and a coating device. The molten metal sodium is located inside the liquefaction tank, and the coating device is located below the liquefaction tank.

7. The method for replenishing sodium in a sodium ion battery according to claim 4, characterized in that: A roller assembly is also provided between the pole piece sodium supplement device and the circulating hot air system.

8. The method for replenishing sodium in a sodium ion battery according to claim 4, characterized in that: The sodium-ion battery sodium replenishing device also includes a pole piece unwinding assembly and a pole piece winding assembly, wherein the pole piece unwinding assembly is located at the starting position of the sodium-ion battery sodium replenishing device, and the pole piece winding assembly is located at the end position of the sodium-ion battery sodium replenishing device.

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