A positive electrode material, a preparation method thereof, a positive electrode sheet, a preparation method and application thereof

Abstract

The application relates to the field of batteries, in particular to a positive electrode material and a preparation method thereof, a positive electrode sheet and a preparation method and application thereof, and comprises the following steps: under a closed condition, a Prussian blue material is subjected to first drying, and then is subjected to first mixing treatment with CO2; the pressure of the first mixing treatment is 50-200 KPa; the time of the first mixing treatment is 30-240 min; and the temperature of the first mixing treatment is 20-30 DEG C. The preparation method of the positive electrode material can effectively reduce the hygroscopicity of the positive electrode material by mixing the dried Prussian blue material with CO2 under a specific pressure condition.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a positive electrode material and a preparation method thereof, a positive electrode sheet and a preparation method and application thereof. BACKGROUND

[0002] After the crystal water of the Prussian blue material is completely removed, the crystal structure is converted into a rhombic crystal system. The Prussian blue material in the rhombic crystal system is easy to absorb water when exposed to air, and is reconverted into a monoclinic structure containing crystal water. Therefore, how to reduce the content of crystal water of the Prussian blue material and how to reduce the hygroscopic property of the Prussian blue material become technical problems to be solved.

[0003] In the prior art, neutral ligands L are often used to participate in the coordination of transition metals M, and partially or completely replace the coordinated water, so as to reduce the water absorption property of the Prussian blue positive electrode material. However, the neutral ligands in this method cannot exchange with the water (crystal water) in the interstitial site, and the content of the water in the interstitial site is much greater than that of the water in the defect site, so this method cannot completely solve the problems of water removal and moisture absorption. Moreover, the exchanged ligands H3CN, NH3, CO and C5H5N are easy to be electrochemically oxidized and decomposed at high potential, which may damage the material structure and cause the performance of the battery to decay.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] In one aspect of the present application, a preparation method of a positive electrode material is provided, which comprises the following steps:

[0006] The Prussian blue material is first dried under a closed condition, and then is subjected to a first mixing treatment with CO2;

[0007] The pressure of the first mixing treatment is 50-200 KPa;

[0008] The time of the first mixing treatment is 30-240 min;

[0009] The temperature of the first mixing treatment is 20-30℃.

[0010] In the preparation method of the positive electrode material, the dried Prussian blue material is mixed with CO2 under a specific pressure condition, and the prepared positive electrode material can effectively reduce the hygroscopic property of the positive electrode material.

[0011] According to another aspect of the present application, the present application also relates to a positive electrode material, which is mainly prepared by the preparation method of the positive electrode material.

[0012] The positive electrode material is treated with CO2 under specific conditions, and CO2 occupies the pore position or defect position of the original crystal water of the Prussian blue material, thereby reducing the moisture absorption rate of the Prussian blue material.

[0013] According to another aspect of the present application, the present application also relates to a preparation method of a positive electrode tab, comprising the following steps:

[0014] The positive electrode tab substrate is subjected to a second drying under a closed condition, and then is subjected to a second mixing treatment with CO2;

[0015] The pressure of the second mixing treatment is 50-200 KPa, the time of the second mixing treatment is 30-240 min, and the temperature of the first mixing treatment is 20-30 DEG C.

[0016] The positive electrode tab substrate comprises a positive electrode current collector and a positive electrode slurry layer arranged on at least one side surface of the positive electrode current collector, and the positive electrode slurry layer comprises a positive electrode material.

[0017] The positive electrode material is a Prussian blue material, or the positive electrode material is prepared by the preparation method of the positive electrode material.

[0018] The preparation method of the positive electrode tab is simple and easy to operate, does not need to rely on complex instruments and equipment, has low preparation cost, and the prepared positive electrode tab has low moisture absorption and good quality.

[0019] According to another aspect of the present application, the present application also relates to a positive electrode tab, which is mainly prepared by the preparation method of the positive electrode tab.

[0020] The positive electrode tab is not easy to absorb water, and can improve the performance of the battery.

[0021] According to another aspect of the present application, the present application also relates to a sodium ion battery and / or a lithium ion battery comprising the positive electrode tab.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) The preparation method of the positive electrode material provided by the present application mixes the dried Prussian blue material with CO2 under specific pressure conditions, which is simple and easy to operate, and the prepared positive electrode material has excellent quality and significantly reduced water absorption performance compared with the prior art.

[0024] (2) The preparation method of the positive electrode tab provided by the present application mixes with CO2 under specific conditions, which is simple and easy to operate compared with the prior art, and the prepared positive electrode tab has excellent quality, is not easy to absorb water, and can improve the performance of the battery.

[0025] (3) The positive electrode material or the positive electrode tab for the preparation of the sodium ion battery can improve the coulomb efficiency and reversible capacity of the battery, and can also improve the cycle performance of the sodium ion battery and reduce the probability of battery swelling. The first mixing treatment does not need to increase additional equipment, and the operation is simple, which brings great benefits to the processing performance of the Prussian blue material in the sodium / potassium ion battery. The CO2 gas adsorbed by the Prussian blue material can be desorbed in the baking step before the battery is injected with liquid, without adversely affecting the performance of the battery such as swelling. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely in combination with the specific embodiments below, but those skilled in the art will understand that the following described embodiments are part of the embodiments of the present application, not all the embodiments, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application. The specific conditions are not specified in the embodiments, which are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, which are conventional products that can be purchased on the market.

[0027] According to one aspect of the present application, the present application relates to a preparation method of a positive electrode material, comprising the following steps:

[0028] The Prussian blue material is first dried under a closed condition, and then subjected to a first mixing treatment with CO2;

[0029] The pressure of the first mixing treatment is 50-200 KPa;

[0030] The time of the first mixing treatment is 30-240 min;

[0031] The temperature of the first mixing treatment is 20-30℃.

[0032] The preparation method of the positive electrode material provided by the present application mixes the dried Prussian blue material with CO2 under a specific pressure condition, which is simple and easy to operate.

[0033] In one embodiment, the pressure of the first mixing treatment may, for example, be, but is not limited to, 50 KPa, 60 KPa, 700 KPa, 80 KPa, 90 KPa, 100 KPa, 110 KPa, 120 KPa, 130 KPa, 140 KPa, 150 KPa, 160 KPa, 170 KPa, 180 KPa or 200 KPa.

[0034] In an embodiment, the first mixing process can be, for example, but not limited to, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 120 min, 140 min, 160 min, 170 min, 180 min, 200 min, 210 min, 230 min or 240 min.

[0035] In an embodiment, the temperature of the first mixing process can be, for example, but not limited to, 20℃, 22℃, 24℃, 26℃, 28℃ or 30℃.

[0036] The molecular formula of Prussian blue is A x M y M’ 1-y [Fe(CN)6] 1-z nH2O, wherein A is Na or K; M is at least one of Fe, Co, Mn, Ni and Cu; M’ is at least one of Fe, Co, Mn, Ni and Cu; 0≤x≤2; 0<y≤1; 0≤z<1; 0≤n≤3.5.

[0037] The Prussian blue crystal has a three-dimensional framework structure formed by FeC6 and (M y M’ 1-y )N6 octahedrons connected by C≡N, and the alkali metal ions A and the water molecules in the interstitial sites are located in the three-dimensional channels of the framework structure. The ion content of A, the defect concentration of Fe(CN)6, and the presence of water molecules in the interstitial sites and defect sites (collectively referred to as crystal water) in the structure will affect the crystal symmetry of Prussian blue. Generally, the structure is cubic, monoclinic or rhombic.

[0038] The Prussian blue positive electrode material prepared using the aqueous solution coprecipitation method contains about 2 moles of water in the interstitial sites per mole (n=2) and a small amount of coordination water in the defect sites. The higher the concentration of A, the higher the specific capacity of the material, and the smaller the defect z. About 10% of the crystal water can be removed during high-temperature drying (>100℃), and the crystal structure is monoclinic. The crystal water of the Prussian blue material with monoclinic structure needs to be completely removed before the battery is injected with liquid electrolyte. The residual crystal water will enter the electrolyte during the charging process as the alkali metal ions are removed, causing capacity decay and increased gas production.

[0039] The present application utilizes the strong adsorption capacity of Prussian blue material for CO2 gas. After the Prussian blue material is vacuum baked to remove the crystal water, a certain pressure of CO2 is introduced into the oven. The CO2 adsorbs and occupies the pore sites or defect sites of the original crystal water, which can reduce the re-hydration rate of the Prussian blue material. After the processing process is exposed to water vapor in the air, the baking time of the electrode can be shortened.

[0040] Preferably, the raw materials of the Prussian blue material include a hexacyanometalate formed by M' and A, a soluble salt of M, and a first solvent.

[0041] Preferably, the A includes Na and / or K, the M includes at least one of Fe, Co, Mn, Ni, and Cu, and the M' includes at least one of Fe, Co, Mn, Ni, and Cu.

[0042] Preferably, the soluble salt of M includes at least one of a chloride salt, a sulfate salt, a nitrate salt, and an acetate salt.

[0043] Preferably, the first solvent includes water.

[0044] Preferably, the Prussian blue material is mainly prepared by mixing and reacting the raw materials.

[0045] Preferably, the mixing and reacting the raw materials specifically include:

[0046] The solution of the hexacyanometalate formed by M' and A and the solution of the soluble salt of M are added dropwise into a reaction container for reaction, and then subjected to an aging treatment.

[0047] Preferably, the temperature of the reaction is 30-100°C (for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 73°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C).

[0048] Preferably, the time of the aging treatment is 4-72h (for example, 4h, 8h, 12h, 16h, 20h, 24h, 28h, 32h, 34h, 36h, 40h, 44h, 48h, 52h, 56h, 60h, 64h, 68h, or 72h).

[0049] Preferably, the mixing and reacting the raw materials further include solid-liquid separation, water washing, drying, and crushing.

[0050] Preferably, the pressure of the first mixing treatment is 100-200KPa.

[0051] Preferably, the time of the first mixing treatment is 100-240min.

[0052] Preferably, the temperature of the first mixing treatment is 23-27°C.

[0053] Preferably, the temperature of the first drying is 100-200°C (for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C).

[0054] Preferably, the first drying is performed at a vacuum degree of ≤ 100 Pa (e.g., 100 Pa, 90 Pa, 80 Pa, 70 Pa, or 60 Pa).

[0055] Preferably, the first drying is performed for 12-72 h (e.g., 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h, 48 h, 52 h, 56 h, 60 h, 64 h, 68 h, or 72 h).

[0056] According to another aspect of the present application, the present application also relates to a positive electrode material, which is prepared by the method for preparing the positive electrode material.

[0057] The positive electrode material provided by the present application has excellent quality and significantly reduced water absorption.

[0058] According to another aspect of the present application, the present application also relates to a method for preparing a positive electrode sheet, which comprises the following steps:

[0059] The positive electrode sheet substrate is subjected to a second drying under a closed condition, and then subjected to a second mixing treatment with CO2.

[0060] The second mixing treatment is performed at a pressure of 50-200 KPa, for 30-240 min, and at a temperature of 20-30℃.

[0061] The positive electrode sheet substrate comprises a positive electrode current collector and a positive electrode slurry layer arranged on at least one side surface of the positive electrode current collector, and the positive electrode slurry layer comprises a positive electrode material.

[0062] The positive electrode material is a Prussian blue material, or the positive electrode material is prepared by the method for preparing the positive electrode material.

[0063] The method for preparing a positive electrode sheet provided by the present application is mixed with CO2 under specific conditions, which is simple in operation, easy to implement, and can prepare a positive electrode sheet with excellent quality.

[0064] In an embodiment, the pressure of the second mixing treatment can be, but is not limited to, 50 KPa, 60 KPa, 70 KPa, 80 KPa, 90 KPa, 100 KPa, 110 KPa, 120 KPa, 130 KPa, 140 KPa, 150 KPa, 160 KPa, 170 KPa, 180 KPa, or 200 KPa.

[0065] In an embodiment, the second mixing process can be, for example, but not limited to, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 120 min, 140 min, 160 min, 170 min, 180 min, 200 min, 210 min, 230 min, or 240 min.

[0066] In an embodiment, the second mixing process can be, for example, but not limited to, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 120 min, 140 min, 160 min, 170 min, 180 min, 200 min, 210 min, 230 min, or 240 min.

[0067] The crystal water is usually removed by heating and baking in a vacuum environment. The baking can be performed when the Prussian blue powder is dried, or the Prussian blue positive electrode sheet is baked, or the battery roll core containing the Prussian blue positive electrode sheet is baked. After baking, it is usually necessary to operate in a low-humidity environment to prevent the Prussian blue material from reabsorbing moisture. Reducing the moisture absorption performance of the Prussian blue material can reduce the requirement for environmental humidity during battery processing. After a small amount of moisture absorption, the crystal water in the Prussian blue material can be removed again by vacuum baking, thereby reducing the baking time.

[0068] Preferably, the second drying temperature is 100-200°C (for example, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C).

[0069] Preferably, the second drying time is 10-72h (for example, 12h, 16h, 20h, 24h, 28h, 32h, 36h, 40h, 44h, 48h, 52h, 56h, 60h, 64h, 68h, or 72h).

[0070] Preferably, the second drying vacuum degree is ≤100Pa (for example, 100Pa, 90Pa, 80Pa, 70Pa, 60Pa, or 50Pa).

[0071] Preferably, the preparation method of the positive electrode sheet substrate comprises the following steps:

[0072] The positive electrode material, the conductive agent, the binder, and the solvent are mixed to obtain a positive electrode slurry. The positive electrode slurry is coated on at least one side surface of the positive electrode current collector, and then a third drying process is performed.

[0073] Preferably, the mass ratio of the positive electrode material, the conductive agent, and the binder is (85-95):(1-10):(2-6) (for example, 85:1:2, 95:10:6, 90:5:4, 88:7:3, or 94:6:3).

[0074] Preferably, the conductive agent includes at least one of activated carbon, acetylene black, ketjen black, flake graphite, carbon nanotube, and graphene.

[0075] Preferably, the binder includes at least one of polyvinylidene fluoride (PVDF), methyl cellulose (CMC), styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), and polyacrylic system (LA).

[0076] Preferably, the viscosity of the cathode slurry is 1500 ~ 10000 Pa·s (e.g., 1500 Pa·s, 2000 Pa·s, 3000 Pa·s, 5000 Pa·s, 7000 Pa·s, 9000 Pa·s, or 10000 Pa·s).

[0077] Preferably, the surface density of the cathode current collector coated with the cathode slurry is 10 ~ 50 mg / cm 2 (e.g., 10 mg / cm 2 , 15 mg / cm 2 , 20 mg / cm 2 , 25 mg / cm 2 , 30 mg / cm 2 , 35 mg / cm 2 , 40 mg / cm 2 , 45 mg / cm 2 , or 50 mg / cm 2 ).

[0078] Preferably, the thickness of the current collector is 10 ~ 45 µm (e.g., 10 µm, 15 µm, 20 µm, 25 µm, 30 µm, 35 µm, 40 µm, or 45 µm).

[0079] Preferably, the thickness of the cathode tab is 50 ~ 200 µm (e.g., 50 µm, 70 µm, 90 µm, 110 µm, 130 µm, 150 µm, 170 µm, 190 µm, or 200 µm).

[0080] Preferably, the temperature of the third drying is 120 ~ 150 °C (e.g., 120 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C, or 150 °C), the time of the third drying is 10 ~ 72 h (e.g., 12 h, 16 h, 20 h, 24 h, 28 h, 32 h, 36 h, 40 h, 44 h, 48 h, 52 h, 56 h, 60 h, 64 h, 68 h, or 72 h), and the vacuum degree of the third drying is ≤ 100 Pa (e.g., 100 Pa, 90 Pa, 80 Pa, 70 Pa, 60 Pa, or 50 Pa).

[0081] According to another aspect of the present application, the present application also relates to a positive electrode sheet, which is mainly prepared by the preparation method of the positive electrode sheet.

[0082] The positive electrode sheet provided by the present application has lower hygroscopicity, and can improve the performance of the battery when used for the preparation of the battery.

[0083] According to another aspect of the present application, the present application also relates to a sodium-ion battery and / or a lithium-ion battery comprising the positive electrode sheet.

[0084] Preferably, the sodium-ion battery comprises the positive electrode sheet and a negative electrode sheet.

[0085] Preferably, the negative electrode sheet is mainly prepared by coating a slurry of hard carbon, a conductive agent and a binder on the surface of an aluminum foil and then performing a fourth drying.

[0086] Preferably, the mass ratio of the hard carbon, the conductive agent and the binder is (90-95):(5-8):(5-8).

[0087] Preferably, the vacuum degree of the fourth drying is ≤133 Pa.

[0088] Preferably, the temperature of the fourth drying is 80-120℃.

[0089] Preferably, the time of the fourth drying is 10-72h.

[0090] The present application will be further explained in conjunction with specific examples and comparative examples.

[0091] Example 1

[0092] The preparation method of the Prussian blue material provided by the present embodiment comprises the following steps:

[0093] 1. 10L of 0.3M Na4Fe(CN)6 and 6L of 0.5M Mn(CH3COO)2 are simultaneously and slowly added to a reaction kettle with stirring, the reaction temperature is 60℃, and after the addition is completed, aging is performed for 40h;

[0094] 2. The Prussian blue material obtained in step 1 is precipitated, filtered, washed with water, dried and crushed;

[0095] 3. The Prussian blue powder obtained in step 2 is baked at 120℃ under a vacuum degree of 100Pa for 48h, cooled to room temperature 25℃ while maintaining the vacuum environment, then high-purity CO2 gas is introduced into the oven, the pressure is maintained at 200KPa for 30min.

[0096] Example 2

[0097] The preparation method of the Prussian blue material provided in the embodiment comprises the following steps:

[0098] 1, 5L 0.6M Na4Fe(CN)6 and 5L 0.6M CoCl2 are simultaneously and slowly added to a reaction kettle with stirring, the reaction temperature is 100 DEG C, and after the addition is completed, aging is performed for 4h;

[0099] 2, the Prussian blue material obtained in step 1 is precipitated and subjected to filtration, water washing, drying and crushing;

[0100] 3, the Prussian blue powder obtained in step 2 is baked at 100 DEG C under a vacuum degree of 100Pa for 72h, cooled to room temperature 25 DEG C in a vacuum environment, then high-purity CO2 gas is introduced into the oven, the pressure is maintained at 100KPa, and the time is 120min.

[0101] Example 3

[0102] The preparation method of the Prussian blue material provided in the embodiment comprises the following steps:

[0103] 1, 30L 0.1M Na4Fe(CN)6 and 6L 0.5M FeSO4 are simultaneously and slowly added to a reaction kettle with stirring, the reaction temperature is 30 DEG C, and after the addition is completed, aging is performed for 72h;

[0104] 2, the Prussian blue material obtained in step 1 is precipitated and subjected to filtration, water washing, drying and crushing;

[0105] 3, the Prussian blue powder obtained in step 2 is baked at 200 DEG C under a vacuum degree of 50Pa for 12h, cooled to room temperature 25 DEG C in a vacuum environment, then high-purity CO2 gas is introduced into the oven, the pressure is maintained at 50KPa, and the time is 240min.

[0106] Example 4

[0107] The preparation method of the positive electrode sheet provided in the embodiment comprises the following steps:

[0108] 1, 10L 0.3M Na4Fe(CN)6 and 6L 0.5M Mn(CH3COO)2 are simultaneously and slowly added to a reaction kettle with stirring, the reaction temperature is 60 DEG C, and after the addition is completed, aging is performed for 40h;

[0109] 2, the Prussian blue material obtained in step 1 is precipitated and subjected to filtration, water washing, drying and crushing;

[0110] 3, the Prussian blue material obtained in step 2, a conductive agent and a binder are mixed into a slurry according to a mass ratio of 90:5:5, coated on an aluminum foil, dried at 110 DEG C for 48h, and rolled;

[0111] 4. Continue baking at 120°C for 48h under 50Pa vacuum, cool to room temperature, introduce high-purity CO2 gas into the oven, maintain a pressure of 200KPa for 30min, and obtain the positive electrode sheet after cooling to room temperature.

[0112] Example 5

[0113] The preparation method of the positive electrode sheet provided in this example comprises the following steps:

[0114] 1. 5L of 0.6M Na4Fe(CN)6 and 5L of 0.6M CoCl2 are simultaneously and slowly added to a stirred reaction kettle, the reaction temperature is 100°C, and the obtained Prussian blue material is aged for 4h after the addition is completed;

[0115] 2. The obtained Prussian blue material in step 1 is precipitated, filtered, washed with water, dried, and crushed;

[0116] 3. The obtained Prussian blue material in step 2, a conductive agent, and a binder are mixed according to a mass ratio of 92:4:4 to form a slurry, which is coated on an aluminum foil, dried at 110°C for 72h under a vacuum degree of 100Pa, and rolled;

[0117] 4. The electrode sheet is baked at 120°C for 48h under a vacuum degree of 100Pa, then cooled to room temperature, high-purity CO2 gas is introduced into the oven, a pressure of 100KPa is maintained for 120min, and the electrode sheet is taken out after cooling to room temperature.

[0118] Example 6

[0119] The preparation method of the positive electrode sheet provided in this example comprises the following steps:

[0120] 1. 30L of 0.1M Na4Fe(CN)6 and 6L of 0.5M FeSO4 are simultaneously and slowly added to a stirred reaction kettle, the reaction temperature is 30°C, and the obtained Prussian blue material is aged for 72h after the addition is completed;

[0121] 2. The obtained Prussian blue material in step 1 is precipitated, filtered, washed with water, dried, and crushed;

[0122] 3. The obtained Prussian blue material in step 2, a conductive agent, and a binder are mixed according to a mass ratio of 90:5:5 to form a slurry, which is coated on an aluminum foil, dried at 150°C for 10h under a vacuum degree of 50Pa, and rolled;

[0123] 4. The electrode sheet is baked at 100°C for 72h under a vacuum degree of 50Pa, cooled to room temperature, high-purity CO2 gas is introduced into the oven, a pressure of 50KPa is maintained for 240min, and the electrode sheet is taken out after cooling to room temperature.

[0124] Comparative Example 1

[0125] The preparation method of the Prussian blue material provided by the present comparative example comprises the following steps:

[0126] 1. The same as Example 1;

[0127] 2. The same as Example 1;

[0128] 3. The Prussian blue powder is baked at 120°C for 48h under vacuum, and cooled to room temperature 25°C while maintaining the vacuum environment.

[0129] Comparative Example 2

[0130] The preparation method of the positive electrode sheet provided by the present comparative example comprises the following steps:

[0131] 1. The same as Example 4;

[0132] 2. The same as Example 4;

[0133] 3. The same as Example 4;

[0134] 4. Baking at 120°C for 48h under a vacuum degree of 100Pa, and cooling to room temperature.

[0135] Experimental Example

[0136] The Prussian blue materials prepared in Examples 1-3 and Comparative Example 1 are placed in an atmospheric environment with a humidity of 60% and a temperature of 25°C, and the water absorption rate of the Prussian blue materials is tested by using a balance weighing method and a moisture content instrument-Karl-Fischer moisture meter. The water content test cutoff temperature is 200°C, and the results are shown in Table 1.

[0137] Table 1 Moisture absorption rate of different treatments

[0138]

[0139]

[0140] As can be seen from the test data in Table 1, the Prussian blue material of Comparative Example 1 has not been subjected to carbon dioxide adsorption, and after drying and dehydration, it is quickly absorbed when exposed to a high humidity environment. The Prussian blue materials of Examples 1-3 have adsorbed carbon dioxide, and when placed in a high humidity environment, their water absorption rate is significantly reduced.

[0141] When the adsorption pressure of CO2 is larger, the adsorption capacity of the Prussian blue material is stronger, and after a short time of adsorption, the water absorption of the Prussian blue material can be greatly reduced. After the dried Prussian blue positive electrode sheet is treated under the same conditions, similar effects are also obtained.

[0142] The positive electrode sheets and hard carbon negative electrode sheets of Examples 4-6 and Comparative Example 2, polyethylene separators, were laminated to form soft pack batteries in an environment with a relative humidity of 20%, the assembled roll cores were placed in a vacuum oven and baked at 100°C for 24h, then injected with electrolyte, formed, and divided. The performance of the batteries was measured, and the results are shown in Table 2.

[0143] Table 2 Performance of different treatments

[0144]

[0145] As can be seen from the data in Table 2, the soft pack sodium ion batteries assembled from the positive electrode sheets of Examples 4-6 after CO2 adsorption have lower moisture content in the positive electrode sheets before liquid injection, higher formation coulombic efficiency and reversible capacity, and improved cycle performance.

[0146] It should be noted that the above examples are used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art will understand that the technical solutions described in the foregoing examples can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a positive electrode tab, the method comprising the steps of: The method for preparing the positive electrode tab comprises the steps of: The positive electrode tab substrate is subjected to a second drying under a closed condition, and then subjected to a second mixing treatment with CO 2. The second mixing treatment is performed at a pressure of 50-200 KPa, for 30-240 min, and at a temperature of 20-30 ℃. The positive electrode tab substrate comprises a positive electrode current collector and a positive electrode slurry layer arranged on at least one side surface of the positive electrode current collector, wherein the positive electrode slurry layer comprises a positive electrode material, and the method for preparing the positive electrode tab substrate comprises the steps of: mixing the positive electrode material, a conductive agent, a binder, and a solvent to obtain a positive electrode slurry, coating the positive electrode slurry on at least one side surface of the positive electrode current collector, and then performing a third drying treatment. The positive electrode material is a Prussian blue material. The third drying is performed at a temperature of 120-150 ℃, for 10-72 h, and at a vacuum degree of ≤100 Pa.

2. The method of producing a positive electrode sheet according to claim 1, characterized by, The second drying is performed at a temperature of 100-200 ℃.

3. The method of producing a cathode electrode piece according to claim 2, characterized by, The second drying is performed for 10-72 h.

4. The method of producing a positive electrode sheet according to claim 3, characterized by, The second drying is performed at a vacuum degree of ≤100 Pa.

5. The method of making a cathode electrode of claim 1, wherein, The mass ratio of the positive electrode material, the conductive agent, and the binder is (85-95):(1-10):(2-6).

6. The method of producing a cathode electrode piece according to claim 5, characterized by, The conductive agent comprises at least one of activated carbon, acetylene black, ketjen black, flaky graphite, carbon nanotubes, and graphene.

7. The method of making a cathode electrode of claim 5, wherein, The binder comprises at least one of polyvinylidene fluoride, methyl cellulose, styrene butadiene latex, polytetrafluoroethylene, and a polyacrylic acid system.

8. The method of making a cathode electrode of claim 5, wherein, The viscosity of the positive electrode slurry is 1500-10000 Pa·s.

9. The method of producing a cathode electrode piece according to claim 8, characterized by, The face density of the positive electrode slurry layer is 10 to 50 mg / cm 2 . 10.A positive electrode tab prepared by the method according to any one of claims 1-9.

11. Sodium ion battery and / or lithium ion battery, characterized in that The positive electrode tab according to claim 10.

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