Processing device of sodium ion battery positive electrode material and moisture slow-release device of sodium ion battery positive electrode material

Abstract

The utility model discloses a sodium ion battery positive electrode material processing device and a moisture slow-release device thereof, the moisture slow-release device comprises a shell, the shell is a cylindrical piece, the side wall of the shell is provided with an opening, and the shell is internally provided with an accommodating space communicated with the opening; the porous body is installed in the containing space, the porous body is used for storing water, and the water in the porous body is released through the opening. The moisture slow-release device disclosed by the utility model can slowly release moisture and is convenient for quantitatively controlling the water absorption capacity of the sodium-ion battery positive electrode material.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a processing device for a sodium ion battery positive electrode material and a water-release device thereof. Background Art

[0002] Sodium-ion battery cathode materials, due to the high activity of the sodium source, easily react with moisture and carbon dioxide in the air, generating surface residual alkali. This residual alkali not only affects the material's capacity and coulombic efficiency, but also causes gelation during battery manufacturing, making coating impossible. High surface residual alkali in the battery increases the internal resistance, thus shortening the lifespan of the cell and system.

[0003] Among them, in the existing technology, the sodium ion battery positive electrode material is directly allowed to absorb water in the air. The moisture on the surface of the material will rise to more than 1000ppm in a very short time, which is difficult to control. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide a moisture release device that can solve the technical problem of the prior art that the positive electrode material of the sodium ion battery directly absorbs moisture from the air, making it difficult to control the moisture on the material surface.

[0005] According to the moisture release device of the first aspect of the present invention, it includes: a shell, which is a cylindrical part, the side wall of the shell is provided with an opening, and the shell has a receiving space connected to the opening; a porous body, which is installed in the receiving space, the porous body is used to store moisture, and the moisture in the porous body is released through the opening.

[0006] The moisture release device according to the embodiment of the present invention combines a housing and a porous body, enabling quantitative control of material moisture. This device can quantitatively simulate surface moisture in sodium-ion battery cathode materials, enabling evaluation of the impact of moisture on material properties, testing of material air stability, and experiments on slurry stability.

[0007] Optionally, the shell includes: an outer shell, which is a cylindrical member, one end of the outer shell has an open end, and the side wall of the outer shell has the opening; and a top cover, which is arranged on the open end.

[0008] Optionally, the shell further includes: a sealing member, which is provided at the open end and connected to the outer shell and the top cover respectively to close an assembly gap between the outer shell and the top cover.

[0009] Optionally, the porous body includes: a winding core, the winding core is located in the receiving space; and a porous diaphragm, the porous diaphragm is coated on at least a portion of the outer circumference of the winding core.

[0010] Optionally, the roll core is a sponge; and / or the thickness of the porous membrane is 10 μm to 16 μm, and / or the porosity of the porous membrane is 20% to 70%, and / or the porous membrane is a PE membrane or a PP membrane, and / or the porous membrane is a coated membrane or an uncoated membrane.

[0011] Optionally, the ratio of the diameter of the winding core to the inner diameter of the shell is 1 / 2 to 3 / 4.

[0012] Optionally, the opening extends along the circumference of the shell.

[0013] Optionally, there are multiple openings, and the two openings at both ends of the diameter of the shell are symmetrical with respect to the central axis of the shell; and / or, along the axial direction of the shell, the spacing between the end of the shell and the adjacent opening is equal to the spacing between the two adjacent openings.

[0014] According to the second aspect of the present invention, a processing device for a sodium ion battery positive electrode material includes: a drum having a mixing space, wherein the mixing space can accommodate materials; a moisture retarder, wherein the moisture retarder is located in the mixing space, and the moisture retarder is any of the moisture retarders described above.

[0015] Optionally, the processing device for the sodium ion battery positive electrode material further includes: a driving member, which drives the drum to rotate so that the material in the mixing space absorbs the moisture released by the moisture release device.

[0016] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0018] Figure 1 This is a schematic structural diagram of a moisture slow release device according to an embodiment of the present utility model;

[0019] Figure 2 This is a structural schematic diagram of a drum according to an embodiment of the present utility model;

[0020] Figure 3is a schematic diagram of a drum rotating on a horizontal pot mill according to one embodiment of the present utility model;

[0021] Figure 4 The present invention is a flowchart of a method for controlling residual alkali on the surface of a positive electrode material for a sodium ion battery according to an embodiment of the present invention.

[0022] Figure Number:

[0023] Moisture slow release device 10;

[0024] Housing 11; opening 111; outer shell 112; open end 113; top cover 114;

[0025] Porous body 12; winding core 121; porous diaphragm 122;

[0026] Roller 20;

[0027] Horizontal pot mill 30. DETAILED DESCRIPTION

[0028] Reference below Figures 1 to 3 The moisture slow release device 10 according to an embodiment of the present invention is described.

[0029] The moisture slow release device 10 according to the embodiment of the present invention includes: a shell 11 and a porous body 12 .

[0030] Specifically, the shell 11 is a cylindrical member, and the side wall of the shell 11 is provided with an opening 111. The shell 11 has a receiving space connected to the opening 111. The porous body 12 is installed in the receiving space. The porous body 12 is used to store moisture, and the moisture in the porous body 12 is released through the opening 111.

[0031] In other words, the moisture release device 10 according to the embodiment of the present invention is mainly composed of a shell 11 and a porous body 12. The shell 11 is in the shape of a cylindrical member, which facilitates the rotation of the shell 11. A receiving space is formed in the shell 11, and an opening 111 is also opened on the side wall of the shell 11 along the wall thickness direction. The opening 111 is connected to the receiving space. The porous body 12 is installed in the receiving space. The porous body 12 has a porous structure and can store moisture. When the cylindrical shell 11 is rotated, the moisture stored in the porous body 12 can be released to the outside of the shell 11 through the opening 111.

[0032] When the moisture release device 10 of this embodiment is used, the porous body 12 is first installed in the housing 11, and then deionized water is dripped onto the porous body 12. The moisture release device 10 can slowly release water through the opening 111, and the released water contacts the material. In this embodiment, the moisture release device 10 is mainly composed of the housing 11 and the porous body 12, which facilitates the moisture release device 10 to slowly release water.

[0033] It should be noted that the moisture slow release device 10 of the embodiment of the present invention can be applied to the preparation of positive electrode materials for sodium ion batteries, and can quantitatively control the free water content on the surface of the positive electrode materials for sodium ion batteries.

[0034] Thus, the moisture release device 10 according to the embodiment of the present invention combines the housing 11 and the porous body 12, and can achieve quantitative control of the moisture content of the material through the moisture release device 10. By using the moisture release device 10 according to the embodiment of the present invention, the surface moisture content of the positive electrode material of the sodium ion battery can be quantitatively simulated, and the impact of moisture on the material performance can be evaluated, and the air stability test of the material and the slurry stability test can be conducted.

[0035] According to one embodiment of the present invention, the housing 11 includes: an outer shell 112 and a top cover 114. The outer shell 112 is a cylindrical member, one end of the outer shell 112 has an open end 113, the side wall of the outer shell 112 has an opening 111, and the top cover 114 is provided to cover the open end 113. For example, the outer shell 112 is a cylindrical member extending in the vertical direction, and has an open end 113 at the upper end of the outer shell 112, and the open end 113 is connected to the receiving space.

[0036] In this embodiment, the housing 112 has an open end 113 through which the porous body 12 can be installed and removed. After the porous body 12 is installed into the receiving space through the open end 113, the open end 113 can be closed by the top cover 114, facilitating the installation and removal of the porous body 13 without affecting the arrangement of the opening 111.

[0037] Optionally, at least a portion of the shell 11 may be an aluminum shell, a stainless steel shell, a plastic shell, etc. The shell 11 made of the above materials is not easy to react with water and the positive electrode material of the sodium ion battery.

[0038] In some specific embodiments of the present invention, the housing 11 further includes a sealing member disposed at the open end 113 and connected to the outer shell 112 and the top cover 114, respectively, to close the assembly gap between the outer shell 112 and the top cover 114. For example, the sealing member can be an O-ring. In this embodiment, the sealing member improves the sealing effect of the open end 113. The sealing member serves a sealing function, effectively preventing moisture from escaping from the top cover 114 and affecting the slow-release effect.

[0039] According to one embodiment of the present invention, the porous body 12 includes: a core 121 and a porous diaphragm 122, the core 121 is located in the receiving space, and the porous diaphragm 122 is coated on at least a portion of the outer periphery of the core 121. The core 121 can have a porous structure to accommodate moisture, and the porous diaphragm 122 can be coated to achieve uniform release of moisture. For example, the core 121 uses a high-density sponge to store moisture. In this embodiment, the porous body 12 uses a combination of the core 121 and the porous diaphragm 122 to extend the moisture release time, and the moisture release rate can be controlled according to the pore size of the porous structure.

[0040] In some embodiments of the present invention, the core 121 is a sponge, which offers advantages such as convenient water storage, low cost, and easy shape control. Alternatively, a polyurethane sponge can be used as the core 121, with 15-30 layers of a 12μm-thick porous membrane 122 wrapped around the high-density polyurethane sponge to facilitate controlled water release. During operation, deionized water can be weighed using a scale with an accuracy of 0.0001g, dripped onto the polyurethane sponge through a pipette, and then screwed onto the top cap 114 for precise water release.

[0041] Optionally, the hardness of the core 121 can be 20D, 30D, 40D, 50D, 60D, 70D, etc., which has a good water absorption function. For example, the hardness of a high-density sponge is 20D, 30D, 40D, 50D, 60D, 70D, etc.

[0042] According to one embodiment of the present invention, the thickness of the porous membrane 122 is 10μm to 16μm, for example, the thickness of the porous membrane 122 is 10μm, 11μm, 12μm, 13μm, 14μm, 15μm or 16μm, etc., which is convenient for controlling the speed of water release.

[0043] In some specific embodiments of the present invention, the porosity of the porous membrane 122 is 20% to 70%. For example, the porosity of the porous membrane 122 is 20%, 25%, 30%, 40%, 50%, 60% or 70%, etc., which is convenient for controlling the rate of water release.

[0044] According to an embodiment of the present invention, the porous diaphragm 122 is a PE diaphragm or a PP diaphragm, etc., which can be selected according to needs and specific sodium ion battery positive electrode materials.

[0045] In some specific embodiments of the present invention, the porous membrane 122 is a coated membrane or an uncoated membrane. A coated membrane can extend the life of the porous membrane 122, while an uncoated membrane can save costs.

[0046] It should be noted that the porous membrane 122 can meet one or more of the above-mentioned conditions of thickness, porosity, material, etc., and a diversified design of the porous membrane 122 can be achieved.

[0047] According to one embodiment of the present invention, the ratio of the diameter of the core 121 to the inner diameter of the shell 11 is 1 / 2 to 3 / 4. For example, the ratio of the diameter of the core 121 to the inner diameter of the shell 11 is 0.5, 0.55, 0.6, 0.7, 0.72 or 0.75, etc., which enables the moisture release device 10 to not only store more moisture, but also does not affect the release of moisture through the opening 111.

[0048] In some specific embodiments of the present invention, the opening 111 extends along the circumference of the housing 11. For example, if the housing 11 is a cylindrical member extending vertically upward, the opening 111 extends along a portion of the outer circumference of the housing 11. In this embodiment, the opening 111 extends along the circumference of the housing 11, which facilitates the release of moisture through the opening 111 when the housing 11 rotates.

[0049] According to one embodiment of the present invention, there are multiple openings 111, and the two openings 111 at opposite ends of the diameter of the housing 11 are symmetrical with respect to the central axis of the housing 11. For example, the housing 11 extends vertically, and relative to the vertically extending central axis of the housing 11, one opening 111 can be provided on the left side of the central axis, and another opening 111 can be provided on the right side. These two openings 111 can be symmetrical with respect to the central axis. In this embodiment, by adopting an axisymmetric two-sided design, it is effectively ensured that the material can quickly and evenly contact the moisture release device 10, thereby ensuring uniform water absorption by the material.

[0050] In some specific embodiments of the present invention, along the axial direction of the shell 11, the distance between the end of the shell 11 and adjacent openings 111 is equal to the distance between two adjacent openings 111. For example, the shell 11 extends vertically, and the multiple openings 111 spaced apart in the vertical direction can virtually divide the shell 11 into cells of equal size in the vertical direction, which is also conducive to ensuring that the material can quickly and evenly contact the moisture release device 10, thereby ensuring uniform water absorption by the material.

[0051] Optionally, the number of openings 111 is four, and the four openings 111 are divided into two groups, specifically a first group of openings and a second group of openings. The first group of openings includes two axially symmetrical openings 111, and the second group of openings also includes two axially symmetrical openings 111. For example, the housing 11 extends vertically, and the first and second groups of openings are spaced apart in the vertical direction. The first group of openings includes one opening 111 located to the left of the central axis and another opening 111 located to the right. Similarly, the second group of openings includes one opening 111 located to the left of the central axis and another opening 111 located to the right.

[0052] Optionally, the length of the shell 112 is between 10 mm and 100 mm, and the diameter is between 10 mm and 30 mm. For example, the length of the shell 112 is 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 80 mm or 100 mm, and the diameter is 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 25 mm or 30 mm, etc., and it can be in contact with sodium ion positive electrode materials of various contents and sizes, so that it can be suitable for the preparation of positive electrode materials for various sodium ion batteries.

[0053] The manufacturing process of the moisture slow release device 10 according to the embodiment of the present invention will be described in detail below with reference to specific embodiments.

[0054] (1) Using an 18650 aluminum shell (i.e., the outer shell 112), four narrow slits (i.e., openings 111) with a projection length of 5 mm and a width of 0.001 to 0.003 mm are cut on the aluminum shell circular tube through a wire cutting process with an accuracy of ±0.001 mm. The positions of the narrow slits are at the positions of 1 / 3 and 2 / 3 of the height from the bottom of the aluminum shell, and an axisymmetric two-side design is adopted. This ensures that the material can quickly and evenly contact the moisture release device 10, thereby ensuring the uniformity of the water absorption of the material.

[0055] (2) A polyurethane sponge is used as the core 121. The ratio of the diameter of the core 121 to the inner diameter of the shell 112 is between 1 / 2 and 3 / 4. The diameter of the core 121 is related to the amount of water added. The deionized water added to the water release device 10 is completely absorbed by the high-density polyurethane sponge, and no large particles of water droplets appear, which can ensure that the water is slowly released from the polyurethane sponge.

[0056] (3) Wrap 15 layers of a porous membrane 122 with a thickness of 12 μm on the surface of a high-density polyurethane sponge, place the porous body 12 with the core 121 wrapped with the porous membrane 122 in the aluminum shell after wire cutting, and weigh a certain amount of deionized water with a 5 mL pipette and drop it into the core 121 in the aluminum shell.

[0057] The present invention also provides a processing device for sodium-ion battery positive electrode materials, comprising: a drum 20 and a moisture retarder 10. The drum 20 has a mixing space that can accommodate material, and the moisture retarder 10 is located within the mixing space. The moisture retarder 10 is a moisture retarder 10 according to any of the above-described embodiments. That is, because the housing 11 is a cylindrical structure, the housing 11 can also move and even rotate within the drum 20 when the drum 20 rotates. That is, when the moisture retarder 10 and the material are together within the drum 20, moisture is released and absorbed by the material simultaneously.

[0058] According to one embodiment of the present invention, the processing device for sodium ion battery positive electrode materials further includes a driving member, which drives the roller 20 to rotate so that the material in the mixing space absorbs the moisture released by the moisture release device 10.

[0059] Optionally, the driving member is a horizontal pot mill 30, and the roller 20 can be driven to rotate by the roller of the horizontal pot mill 30, which is convenient for installing and removing the roller 20 and convenient for operation. In addition, the outer circumference of the roller 20 is circular, and the surface of the roller is also circular, which facilitates the smooth rotation of the roller 20.

[0060] The following first describes in detail the quantitative simulation verification process of the sodium ion battery positive electrode material moisture content by the processing device of the sodium ion battery positive electrode material of the present invention in conjunction with specific embodiments.

[0061] (1) Using a balance with an accuracy of 0.0001 g, weigh a certain amount of deionized water that has been calculated, and drip it onto the high-density sponge of the water release device 10 through a 5 mL pipette, and then screw on the 18650 model top cover 114;

[0062] (2) Under a dew point environment of -30°C, the material and the moisture slow release device 10 are placed in a nylon drum 20. The diameter of the nylon drum 20 is 130 mm and the height is 600 mm. The upper cover of the drum 20 is sealed with an O-ring and a screw flange;

[0063] (3) Place the nylon drum 20 containing the test material and the moisture release device 10 on the horizontal pot mill 30, adjust the speed of the drum 20 to 5 rpm-60 rpm, and roll for 2 h-6 h, so that the material is fully in contact with the moisture release device 10 in the drum 20, and the moisture release device 10 slowly releases moisture so that the material absorbs moisture;

[0064] (4) After the test, the material was sampled at a dew point of -30°C and the free water content on the surface of the material was tested using a Mettler-Karl Fischer moisture meter.

[0065] For ease of comparison and illustration, Comparative Example 1, Comparative Example 2, and Examples were set up. In Comparative Example 1, the moisture content of the material was directly tested. In Comparative Example 2, the material was milled in a nylon drum 20 for 3 hours without the addition of a moisture release device 10, and the moisture content was tested. In Examples 1, different deionized water levels were added through the moisture release device 10 and milled together with the material in a nylon drum 20 for 3 hours, and the moisture content was tested. The test results are shown in Table 1 below.

[0066] Table 1

[0067]

[0068] As can be seen from the data in Table 1, the moisture slow release device 10 can quantitatively simulate the free moisture content on the surface of the sodium-ion battery positive electrode material. Moreover, the free moisture content on the surface of the sodium-ion battery positive electrode material can be quantitatively simulated to avoid direct water absorption by the material, which is uncontrollable. Moreover, by quantitatively simulating the moisture content on the surface of the material, the effects of moisture and surface residual alkali on the physical and chemical properties and electrical properties of the sodium-ion battery positive electrode material can be verified. For example, by quantitatively simulating the moisture content on the surface of the material, the effect of residual alkali on the slurry performance of the sodium-ion battery positive electrode material can be verified.

[0069] The following combination Figures 1 to 4 And the specific embodiment describes in detail the working process of the processing device of the sodium ion battery positive electrode material according to the embodiment of the utility model.

[0070] According to an embodiment of the present invention, a method for controlling residual alkali on the surface of a positive electrode material for a sodium ion battery comprises the following steps:

[0071] Sintering and crushing the positive electrode material of the sodium ion battery;

[0072] The crushed material and the moisture retarder 10 are placed in the drum 20. The drum 20 rotates so that the material and the moisture retarder 10 come into contact. The moisture retarder 10 releases moisture so that the material absorbs moisture.

[0073] The material that has absorbed moisture is sealed in an argon atmosphere and then baked to generate sodium hydroxide in situ. The moisture slow release device 10 is any of the moisture slow release devices 10 described above.

[0074] In other words, the method for controlling the surface residual alkali of the positive electrode material of a sodium ion battery according to an embodiment of the present invention can realize the control of the residual alkali content on the surface of the positive electrode material of the sodium ion battery. The specific method may include the following steps:

[0075] First, the finished sodium ion battery cathode material is sintered and crushed to facilitate the subsequent control of the moisture content of the material through the moisture release device 10. For example, the finished sodium ion battery cathode material is pre-fired in a nitrogen atmosphere to allow the moisture in the material to escape and the sodium carbonate to react into the material lattice.

[0076] Secondly, the crushed material and the moisture retarder 10 are placed together in the drum 20, and the drum 20 is driven to rotate. The material inside the drum 20 collides with the moisture retarder 10, and the moisture retarder 10 releases moisture in the drum 20. The rotation of the drum 20 can make the material and the moisture retarder 10 fully contact, and the moisture retarder 10 releases moisture to allow the material to absorb moisture. By controlling the rotation speed and size of the drum 20, the contact degree between the moisture retarder 10 and the material can be controlled. By controlling the speed at which the moisture retarder 10 releases water, the amount of moisture absorbed by the material can be controlled. In other words, the drum 20 and the moisture retarder 10 can cooperate with each other to make the sodium cathode material absorb water in situ, and the water absorption of the material can be accurately controlled, thereby achieving quantitative control of the moisture content of the material.

[0077] Again, the material that has absorbed moisture is sealed in an argon atmosphere and then baked to generate sodium hydroxide in situ. That is, by allowing the material to fully react with moisture at high temperature under an argon protection environment to prepare sodium hydroxide, in-situ grown sodium hydroxide can be prepared, and the residual alkali content on the surface of the sodium hydroxide can be precisely controlled, and the influence of the residual alkali of sodium carbonate on the surface can be eliminated.

[0078] Therefore, according to the method for controlling the surface residual alkali of the positive electrode material of the sodium ion battery of the embodiment of the present utility model, the crushed material and the moisture retarder 10 are placed in the drum 20, and the drum 20 is rotated to make the material contact with the moisture retarder 10, and the moisture retarder 10 releases moisture so that the material absorbs moisture, which is conducive to achieving precise control of the moisture in the material, and then the material that has absorbed moisture is sealed and baked in an argon atmosphere to generate sodium hydroxide in situ, which is conducive to quantitative control of the content of generated NaOH. In addition, after research, it was found that the cause of gelation of sodium ion batteries during the slurrying process is the surface residual alkali of the material particles; therefore, the method for controlling the surface residual alkali of the positive electrode material of the sodium ion battery of the embodiment of the present utility model is conducive to quantitative simulation of the surface residual alkali of the positive electrode material of the sodium ion battery, so that the influence of the residual alkali on the physical and chemical properties and electrical properties of the material can be quantified, guiding material preparation, and improving problems such as gelation at the end of the battery cell during the slurrying process.

[0079] According to one embodiment of the present invention, the conditions for baking the sealed material include: baking at 60°C and baking for 72h-240h. For example, the material after the test is completed is sampled under a dew point environment of -30°C, placed in a glove box, sealed with an aluminum foil ziplock bag under an argon atmosphere, and then transferred to a 60°C oven and baked for 72h-240h. In this embodiment, the material that has absorbed moisture is sealed and baked in an argon atmosphere, and the conditions for baking the sealed material include: baking at 60°C and baking for 72h-240h, such as baking for 72h, 80h, 90h, 100h, 120h, 150h, 200h, 230h or 240h, etc., which is conducive to allowing the material to fully react with moisture and prepare in-situ grown sodium hydroxide.

[0080] In some specific embodiments of the present invention, the step of sealing the material includes: sampling the material that has absorbed moisture at a dew point of -30°C, placing it in a glove box, and sealing it with an aluminum foil ziplock bag under an argon atmosphere. For example, the material after the test is completed is sampled at a dew point of -30°C, placed in a glove box, and sealed with an aluminum foil ziplock bag under an argon atmosphere. In this embodiment, by sampling the material that has absorbed moisture at a dew point of -30°C, placing it in a glove box, and sealing it with an aluminum foil ziplock bag under an argon atmosphere, the sealing effect can be improved, and the influence of moisture and carbon dioxide in the air on the control of the residual alkali content on the surface of sodium hydroxide can be avoided.

[0081] In addition, after sampling in the glove box, the moisture content of the material can be tested by the Mettler-Karl Fischer method, and the residual alkali of sodium hydroxide and sodium carbonate on the surface of the material can be tested by titration, which is conducive to accurately obtaining the surface residual alkali content of the sodium ion battery positive electrode material.

[0082] According to one embodiment of the present invention, a method for controlling the residual alkali on the surface of a sodium-ion battery positive electrode material further comprises the following steps: sintering a material that generates sodium hydroxide in situ under a carbon dioxide atmosphere to generate sodium carbonate in situ. For example, by sintering a material with a high NaOH content at low temperature under a high-purity carbon dioxide environment, in-situ generation of sodium carbonate is achieved. In other words, a material with a high sodium hydroxide residual alkali content can be used and sintered under a high-purity carbon dioxide atmosphere to convert the residual alkali on the surface of the material into residual alkali in sodium carbonate, eliminating the influence of the residual alkali in sodium hydroxide, thereby facilitating quantitative control of the content of generated sodium carbonate.

[0083] In some specific embodiments of the present invention, the conditions for sintering the material of in-situ generated sodium hydroxide in a carbon dioxide atmosphere include: in a carbon dioxide environment, a pressure of 5Pa-80Pa, a holding temperature of 300°C-600°C, and a holding time of 3h-60h. For example, under a -30°C dew point environment, the material of in-situ generated sodium hydroxide is loaded into a 330mm*330mm sagger, with a loading capacity of 3kg-7kg, the sagger containing the material is loaded into an atmosphere furnace, 99.9999% pure carbon dioxide is introduced into the atmosphere furnace, the pressure in the furnace is maintained at 5Pa-80Pa, the holding temperature is set at 300°C-600°C, and the holding time is 3h-60h. Optionally, the sintered material can be subsequently transferred to a glove box filled with argon, and the material is pulverized with a small steel mill in the glove box, intermittently pulverized for 5min, and then sealed in an aluminum foil ziplock bag in the glove box. In this embodiment, in a carbon dioxide environment, the pressure is 5Pa-80Pa, for example, the pressure is 5Pa, 10Pa, 15Pa, 20Pa, 30Pa, 40Pa, 50Pa, 60Pa, 70Pa or 80Pa, etc.; the insulation temperature is set to 300℃-600℃, for example, the insulation temperature is 300℃, 350℃, 400℃, 450℃, 500℃ or 600℃, etc.; the insulation time is 3h-60h, for example, the insulation time is 3h, 10h, 20h, 30h, 40h, 50h or 60h, etc. The above conditions are coordinated with each other, which is conducive to converting the residual sodium hydroxide on the surface of the material into residual sodium carbonate.

[0084] According to one embodiment of the present invention, the step of sintering and crushing the positive electrode material of the sodium ion battery includes: sintering the positive electrode material of the sodium ion battery at a high temperature of 800°C-900°C in an atmosphere furnace in a dew point environment of -30°C, introducing nitrogen into the atmosphere furnace during the sintering process, and maintaining the pressure in the atmosphere furnace at 5Pa-80Pa, sintering at a constant temperature for 6h-20h, and maintaining a positive pressure environment in the furnace of 5Pa-80Pa in the heating, constant temperature and cooling sections. For example, take the prepared finished sodium ion battery positive electrode material, in a -30°C dew point environment, use a 330mm*330mm sagger, with a sagger capacity of 3kg-7kg, and perform high-temperature sintering at 800°C-900°C in an atmosphere furnace. During the sintering process, 99.9999% pure nitrogen is introduced into the atmosphere furnace, and the pressure in the atmosphere furnace is maintained at 5Pa-80Pa. The constant temperature sintering is carried out for 6h-20h, and the positive pressure environment in the furnace is maintained at 5Pa-80Pa in the heating, constant temperature and cooling stages. In this embodiment, the sodium ion battery positive electrode material is sintered at a high temperature of 800°C-900°C in an atmosphere furnace in a dew point environment of -30°C, for example, the sintering temperature is 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C or 900°C; nitrogen is introduced into the atmosphere furnace during the sintering process, and the pressure in the atmosphere furnace is maintained at 5Pa-80Pa, for example, the pressure is 5Pa, 15Pa, 20Pa, 25Pa, 30Pa , 40Pa, 50Pa, 60Pa, 70Pa or 80Pa, etc.; constant temperature sintering for 6h-20h, for example, sintering for 6h, 10h, 12h, 15h, 16h, 18h or 20h, etc., the heating, constant temperature and cooling sections all maintain a positive pressure environment in the furnace of 5Pa-80Pa, for example, maintaining 5Pa, 15Pa, 20Pa, 30Pa, 40Pa, 50Pa, 60Pa or 80Pa, etc., through the above conditions, the moisture in the material can be overflowed, and the sodium carbonate reacts into the material lattice.

[0085] Alternatively, the sintered material is transferred to a glove box filled with argon, where the water and oxygen concentrations in the glove box are both less than 0.01 ppm, and the material is pulverized and packaged in the glove box. For example, the sintered material is transferred to a glove box filled with argon, where the water and oxygen concentrations in the glove box are both less than 0.01 ppm, and the argon purity is 99.999%. The material is pulverized in the glove box using a small steel mill, intermittently pulverizing for 5 minutes, and then the material is packaged in the glove box.

[0086] In some specific embodiments of the present invention, the positive electrode material of the sodium ion battery adopts a layered transition metal oxide sodium ion battery positive electrode material, the general formula of which is Na a Cu x Fe y Mn z A1-x-y-z O2, where A is an element that replaces the transition metal by doping, and A is one or more of Li, Ni, Mg, Zn, Co, Al, Zr, and Ti, wherein 0.5<a≤1.1, 0<x≤0.5, 0<y≤0.5, and 0<z≤0.5; the values of a, x, y, and z satisfy the charge balance of the chemical formula. a Cu x Fe y Mn z A 1-x-y-z O2 sodium ion battery positive electrode material is conducive to ensuring that the prepared sodium ion battery has good electrical properties.

[0087] According to one embodiment of the present invention, the rotation speed of the drum 20 is 5rpm-60rpm, and the rolling time is 2h-6h. For example, under a dew point environment of -30°C, the material encapsulated in an argon atmosphere and the moisture retarder 10 are loaded into the nylon drum 20. Optionally, the nylon drum 20 has a diameter of 130mm and a height of 600mm, and the upper cover of the drum 20 is sealed with an O-ring and a screw flange. Optionally, the nylon drum 20 containing the test material and the moisture retarder 10 is placed on the horizontal pot mill 30, and the rotation speed of the drum 20 is adjusted to 5rpm-60rpm, and the rolling time is 2h-6h, so that the material is fully in contact with the moisture retarder 10 in the drum 20, and the moisture retarder 10 slowly releases moisture so that the material absorbs moisture. In this embodiment, the rotation speed of the drum 20 is 5rpm-60rpm, for example, the rotation speed of the drum 20 is 5rpm, 10rpm, 15rpm, 20rpm, 25rpm, 30rpm, 35rpm, 40rpm, 50rpm or 60rpm, etc.; the rolling time is 2h-6h, for example, the rolling time is 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or 6h, etc., which can control the contact time between the material and water, and realize precise control of the water absorption of the material.

[0088] The present invention also discloses a sodium-ion battery positive electrode material, including a positive electrode material prepared by the method for controlling the surface residual alkali of a sodium-ion battery positive electrode material according to any of the above embodiments. Because the method for controlling the surface residual alkali of a sodium-ion battery positive electrode material according to the embodiments of the present invention facilitates quantitative simulation of the surface residual alkali of a sodium-ion battery positive electrode material, the residual alkali content on the surface of the sodium-ion battery positive electrode material according to the embodiments of the present invention can be precisely controlled, and further details are omitted here.

[0089] The present invention also discloses a sodium ion battery, which includes the sodium ion battery positive electrode material of any of the above embodiments. Since the control method of the surface residual alkali of the sodium ion battery positive electrode material according to the embodiment of the present invention is conducive to quantitatively simulating the surface residual alkali of the sodium ion battery positive electrode material, the influence of the residual alkali on the physical and chemical properties and electrical properties of the material can be quantified, which will not be described in detail here.

[0090] The method for controlling the surface residual alkali of the positive electrode material of a sodium ion battery according to the embodiment of the present invention is described in detail below with reference to specific embodiments.

[0091] (1) Making a water release device 10

[0092] First, an 18650 aluminum shell is used, and four narrow slits with a projected length of 5 mm are cut on the aluminum shell circular tube through a wire cutting process with an accuracy of ±0.001 mm. A polyurethane sponge is used as the winding core 121, and 15-30 layers of a porous diaphragm 122 with a thickness of 12 μm are wrapped on the surface of the high-density polyurethane sponge.

[0093] Next, deionized water was weighed using a balance with an accuracy of 0.0001 g, and was dripped onto the polyurethane sponge of the water release device 10 through a pipette, and then the 18650-type aluminum shell cover was screwed on.

[0094] (2) Controlling the surface residual alkali of the positive electrode material of sodium ion batteries

[0095] S1, take the prepared NaCu 1 / 9 Fe 1 / 3 Mn 1 / 3 Ni 2 / 9 The O2 finished material is sintered at 800℃ in an atmosphere furnace in a -30℃ dew point environment using a 330mm*330mm sagger with a loading capacity of 3kg-7kg. During the sintering process, 99.9999% pure nitrogen is introduced into the atmosphere furnace and the pressure in the atmosphere furnace is maintained at 5Pa-80Pa. The sintering is carried out at a constant temperature for 6-20 hours, and a positive pressure environment of 5Pa-80Pa is maintained in the heating, constant temperature and cooling stages.

[0096] S2. The sintered material is transferred to a glove box filled with argon. The water and oxygen concentrations in the glove box are both lower than 0.01 ppm, and the purity of the argon is 99.999%. The material is crushed in the glove box using a small steel mill, and the crushing is intermittent for 5 minutes. The material is then packaged in the glove box.

[0097] S3. Take out the crushed material and perform Mettler Karl Fischer moisture measurement, and use the method with application number 202110377510.0 to perform titration test of sodium hydroxide and sodium carbonate on the material surface.

[0098] S4. In situ generation of sodium hydroxide

[0099] S41. Under a dew point environment of -30°C, the material packaged in an argon atmosphere and the moisture release device 10 are placed into a nylon drum 20. The nylon drum 20 has a diameter of 130 mm and a height of 600 mm. The upper cover of the drum 20 is sealed with an O-ring and a screw flange.

[0100] S42. Place the nylon drum 20 containing the test material and the moisture retarder 10 on the horizontal pot mill 30, adjust the rotation speed of the drum 20 to 5 rpm-60 rpm, and roll for 2 h-6 h, so that the material is fully in contact with the moisture retarder 10 in the drum 20, and the moisture retarder 10 slowly releases moisture so that the material absorbs moisture.

[0101] S43. After the test, sample the material at a -30°C dew point, place it in a glove box, seal it in an aluminum foil ziplock bag under an argon atmosphere, and then transfer it to a 60°C oven for 72-240 hours, i.e., the baking temperature is 60°C. Then, sample it in the glove box and test the material moisture content using the Mettler-Karl Fischer method. Also, test the residual sodium hydroxide and sodium carbonate on the material surface using titration.

[0102] S5. In-situ generation of sodium carbonate:

[0103] S51. Under a dew point environment of -30°C, the high-moisture material prepared in step 5 is loaded into a 330mm*330mm sagger with a loading capacity of 3kg-7kg. The sagger containing the material is loaded into an atmosphere furnace, and 99.9999% pure carbon dioxide is introduced into the atmosphere furnace. The pressure in the furnace is maintained at 5Pa-80Pa, the holding temperature is set to 500°C, and the holding time is 3 hours to 60 hours, that is, the secondary sintering temperature is 500°C;

[0104] S52. The sintered material is transferred to a glove box filled with argon gas, and the material is crushed with a small steel mill in the glove box for 5 minutes intermittently, and then the material is sealed in an aluminum foil ziplock bag in the glove box;

[0105] S53. Test the moisture content of the material by Mettler-Karl Fischer method, and test the residual sodium hydroxide and sodium carbonate on the surface of the material by titration.

[0106] The material prepared in step S1 is used as the control group, and control group 1, control group 2, control group 3 and control group 4 are obtained through different experimental conditions; the material prepared in step S4 is used as the experimental group, and experimental groups 1 to 6 are obtained through different experimental conditions; the material prepared in step S5 is used as the experimental group, and experimental groups 7 and 8 are obtained through different experimental conditions. The materials of the above experimental groups and control groups are tested, and the test results shown in Table 2 below are obtained.

[0107] Table 2

[0108]

[0109]

[0110] The following is an explanation of Table 2:

[0111] (1) It can be seen from control group 2 that after baking at 800℃ for 12 hours, the moisture content of the material is extremely low, and the residual alkali of NaOH reacts with the residual alkali of sodium carbonate to decompose;

[0112] (2) It can be seen from control groups 3 and 4 that the material absorbs water through the slow-release device, and the free moisture of the material after water absorption is consistent with the designed added moisture;

[0113] (3) It can be seen from experimental groups 1, 2, 3, 4, and 5 that by quantitatively absorbing water from the material and baking it at 60°C for 120 hours, the water is completely converted into NaOH;

[0114] (4) It can be seen from experimental groups 6 and 7 that by sintering the high NaOH residual alkali material in a carbon dioxide environment for 36 hours, all NaOH was converted into sodium carbonate;

[0115] (5) For the control group and the experimental group, the powder resistivity was tested using a pressure of 14 kN and a pressure of 105.5 MPa. The test results are shown in Table 3 below.

[0116] Table 3

[0117]

[0118]

[0119] The following conclusions can be drawn from the above experimental and control groups:

[0120] First, by pre-calcining in a nitrogen atmosphere, the moisture in the material is overflowed, and the sodium carbonate reacts into the material lattice. As a blank control group, the blank control group and the moisture release device 10 are used to make the sodium cathode material absorb water in situ, and the water absorption of the material can be accurately controlled;

[0121] Secondly, by fully reacting the material with water at high temperature under an argon protection environment to prepare sodium hydroxide, in-situ grown sodium hydroxide can be prepared, and the residual alkali content on the surface of the sodium hydroxide can be accurately controlled, and the influence of the residual alkali of sodium carbonate on the surface can be eliminated;

[0122] Third, a material with high sodium hydroxide residual alkali content is used and sintered in a high-purity carbon dioxide atmosphere to convert the hydroxide residual alkali on the surface of the material into sodium carbonate residual alkali, and eliminate the influence of the sodium hydroxide residual alkali.

[0123] In summary, the moisture release device 10 of the embodiment of the present invention can quantitatively control the moisture content of the material, thereby controlling the content of residual sodium hydroxide and residual sodium carbonate on the surface, avoiding cross-influence, and supporting the research on material properties.

[0124] The positive electrode material of the sodium ion battery according to the embodiment of the present invention and other components and operations of the battery are well known to those skilled in the art and will not be described in detail here.

[0125] In the description of the present invention, it should be understood that the terms "center", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "inside", "outside", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0126] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0127] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "example," "specific example," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0128] Although the embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and purpose of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A water slow release device (10), characterized in that: include: A housing (11), wherein the housing (11) is a cylindrical member, a side wall of the housing (11) is provided with an opening (111), and a receiving space in communication with the opening (111) is provided in the housing (11); A porous body (12) is installed in the receiving space, the porous body (12) is used to store moisture, and the moisture in the porous body (12) is released through the opening (111).

2. The moisture slow release device (10) according to claim 1, characterized in that: The housing (11) comprises: A housing (112), wherein the housing (112) is a cylindrical member, one end of the housing (112) has an open end (113), and a side wall of the housing (112) has the opening (111); A top cover (114) is provided on the open end (113).

3. The moisture slow release device (10) according to claim 2, characterized in that: The housing (11) further comprises: A sealing member is provided at the open end (113) and is connected to the outer shell (112) and the top cover (114) respectively to close an assembly gap between the outer shell (112) and the top cover (114).

4. The moisture slow release device (10) according to claim 1, characterized in that: The porous body (12) comprises: a winding core (121), the winding core (121) being located in the receiving space; A porous diaphragm (122) is coated on at least a portion of the outer periphery of the winding core (121).

5. The moisture slow release device (10) according to claim 4, characterized in that: The winding core (121) is a sponge; and / or the thickness of the porous membrane (122) is 10 μm to 16 μm, and / or the porosity of the porous membrane (122) is 20% to 70%, and / or the porous membrane (122) is a PE membrane or a PP membrane, and / or the porous membrane (122) is a coated membrane or an uncoated membrane.

6. The moisture slow release device (10) according to claim 4, characterized in that: The ratio of the diameter of the winding core (121) to the inner diameter of the shell (11) is 1 / 2 to 3 / 4.

7. The moisture slow release device (10) according to claim 1, characterized in that: The opening (111) extends along the circumference of the housing (11).

8. The moisture slow release device (10) according to claim 7, characterized in that: The number of the openings (111) is multiple, and the two openings (111) at the two ends of the diameter of the shell (11) are symmetrical with respect to the central axis of the shell (11); and / or, along the axial direction of the shell (11), the spacing between the end of the shell (11) and the adjacent openings (111) is equal to the spacing between the two adjacent openings (111).

9. A processing device for a sodium ion battery positive electrode material, characterized in that: include: A drum (20), wherein the drum (20) has a mixing space, and the mixing space can accommodate materials; A moisture slow release device (10), the moisture slow release device (10) is located in the mixing space, and the moisture slow release device (10) is the moisture slow release device (10) according to any one of claims 1-8.

10. The processing device for sodium ion battery positive electrode material according to claim 9, characterized in that: Also includes: A driving member drives the drum (20) to rotate so that the material in the mixing space absorbs the moisture released by the moisture release device (10).

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