Sodium-ion battery cathode hybrid material, electrode sheet, slurry and preparation method

Abstract

The present invention provides a positive electrode hybrid material, a pole piece, a slurry and a preparation method for a sodium-ion battery. Among them, the positive electrode hybrid material for the sodium-ion battery includes: a binder, a conductive additive, and an active material for the sodium-ion battery; wherein, the binder is SEBS rubber. In the positive electrode hybrid material for the sodium-ion battery of the present invention, SEBS rubber is used as the binder to make a positive electrode pole piece for the sodium-ion battery. By utilizing the chemical stability of SEBS rubber itself and the stability of the solvent oil during the preparation of the slurry, it has alkali resistance and antioxidant ability. Therefore, the positive electrode slurry for the sodium-ion battery prepared from the positive electrode hybrid material for the sodium-ion battery has the advantages of good fluidity, good stability, and small viscosity change; it avoids the defect that in the preparation process of the existing positive electrode slurry for the sodium-ion battery, the PVDF binder easily reacts with the strong alkaline substances on the surface of the sodium-ion battery material, resulting in the denaturation and failure of the positive electrode slurry.

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium-ion batteries, and particularly relates to a positive electrode hybrid material, a pole piece, a slurry and a preparation method of a sodium-ion battery. Background Art

[0002] A sodium-ion battery is a secondary battery (rechargeable battery), which mainly works by the movement of sodium ions between the positive electrode and the negative electrode, and has a working principle similar to that of a lithium-ion battery.

[0003] For a traditional sodium-ion battery, PVDF (polyvinylidene fluoride) is often used as a binder in the preparation of its positive electrode pole piece, and NMP (N-methylpyrrolidone) is used as a solvent. The preparation of the positive electrode slurry includes: uniformly mixing and dissolving the PVDF binder with NMP by high-speed homogenization, and then adding a conductive additive and a positive electrode active material to the above binder mixture respectively and stirring evenly at high speed again to finally form a positive electrode slurry with a viscosity of 3000 - 8000 mPa·s. Then, the positive electrode slurry is uniformly coated on a conductive foil, and a positive electrode pole piece of a sodium-ion battery is prepared by drying, rolling, etc.

[0004] In the preparation of the positive electrode slurry, PVDF is used as a binder for the positive electrode active material and the conductive additive. However, the current problem is that the positive electrode material of a sodium-ion battery, especially the layered oxide positive electrode material, often has strong alkalinity, and in the homogenization process of this PVDF binder, it is very easy to react with strong alkali, resulting in the loss of -H and -F groups in PVDF, making PVDF cross-linked and denatured and losing its binding effect. It is manifested that the prepared slurry does not have fluidity and becomes jelly-like, making the subsequent coating process unable to proceed smoothly. Therefore, it is particularly important to develop a binder and solvent system with alkali resistance and apply it to the production of positive electrode sheets of sodium-ion batteries. Summary of the Invention

[0005] To solve the above problems, the present invention provides a positive electrode hybrid material for a sodium-ion battery, including:

[0006] a binder, a conductive additive, and a sodium-ion battery active material;

[0007] wherein, the binder is SEBS rubber.

[0008] Preferably, the SEBS rubber includes one or a combination of two of unmodified SEBS or maleic acid-modified SEBS rubber;

[0009] Preferably, the SEBS rubber is maleic acid-modified SEBS rubber.

[0010] Preferably, the weight percentage of the SEBS rubber in the positive electrode composite material of the sodium-ion battery is 0.1% to 5%;

[0011] Preferably, the weight percentage of the SEBS rubber in the positive electrode composite material of the sodium-ion battery is 1.0% to 3.5%.

[0012] Preferably, the active material of the sodium-ion battery includes one of layered oxides, phosphate compounds, and Prussian compounds;

[0013] Preferably, the layered oxide includes one or more of nickel-iron-manganese-sodium layered oxide, copper-containing nickel-iron-manganese-sodium layered oxide, and iron-manganese-sodium layered oxide;

[0014] Preferably, the phosphate compound includes one or more of sodium iron phosphate, sodium vanadium phosphate, sodium fluorovanadate phosphate, sodium manganese phosphate, and sodium manganese iron phosphate;

[0015] Preferably, the active material of the sodium-ion battery is nickel-iron-manganese-sodium layered oxide or sodium fluorovanadate phosphate.

[0016] Preferably, the conductive additive includes one or more combinations of conductive carbon black, conductive graphite, conductive carbon nanotubes, and conductive graphene;

[0017] Preferably, the conductive additive is conductive carbon black;

[0018] Preferably, the weight percentage of the conductive additive in the positive electrode composite material of the sodium-ion battery is 0.1% to 5%;

[0019] Preferably, the weight percentage of the conductive additive in the positive electrode composite material of the sodium-ion battery is 1.5% to 3.5%.

[0020] In addition, to solve the above problems, the present invention also provides a positive electrode plate of a sodium-ion battery, including the positive electrode composite material of the sodium-ion battery as described above, and a current collector aluminum foil.

[0021] In addition, to solve the above problems, the present invention also provides a positive electrode slurry of a sodium-ion battery, including the positive electrode composite material of the sodium-ion battery as described above, and a solvent oil.

[0022] Preferably, the solvent oil is a solvent oil with an initial boiling point greater than 100°C and a final boiling point less than 250°C, containing or not containing aromatic hydrocarbons;

[0023] Preferably, the solvent oil is solvent oil of grade D85;

[0024] Preferably, the solid content in the positive electrode slurry of the sodium-ion battery is 35% - 75%.

[0025] In addition, to solve the above problems, the present invention also provides a method for preparing a positive electrode slurry of a sodium-ion battery as described above, including:

[0026] Preparing a first mixture after mixing the binder and the solvent oil;

[0027] Taking the conductive additive and adding it to the first mixture to obtain a second mixture;

[0028] Taking the active material of the sodium-ion battery and adding it to the second mixture to obtain a third mixture;

[0029] Taking the solvent oil and adding it to the third mixture, and adjusting the solid content of the slurry to 35%-75% to obtain the positive electrode slurry of the sodium-ion battery.

[0030] Preferably, after taking the solvent oil and adding it to the third mixture, adjusting the solid content of the slurry to 35%-75% to obtain the positive electrode slurry of the sodium-ion battery, it further includes:

[0031] Taking the positive electrode slurry of the sodium-ion battery and coating it on a current collector aluminum foil on a coater, and after rolling, obtaining a positive electrode plate of the sodium-ion battery.

[0032] The present invention provides a positive electrode hybrid material, electrode plate, slurry and preparation method of a sodium-ion battery. Among them, the positive electrode hybrid material of the sodium-ion battery includes: a binder, a conductive additive, and an active material of the sodium-ion battery; wherein, the binder is SEBS rubber. In the positive electrode hybrid material of the present invention, SEBS rubber is used as the binder to make a positive electrode plate of the sodium-ion battery. Utilizing the chemical stability of SEBS rubber itself and the stability of the solvent oil during the preparation of the slurry, it has alkali resistance and antioxidant ability. Thus, the positive electrode slurry of the sodium-ion battery prepared from the positive electrode hybrid material of the sodium-ion battery has advantages such as good fluidity, good stability, and small viscosity change; it avoids the defect that in the existing preparation process of the positive electrode slurry of the sodium-ion battery, the PVDF binder easily reacts with the strong alkaline substances on the surface of the sodium-ion battery material, causing the positive electrode slurry to denature and fail.

[0033] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments. Detailed Embodiments

[0034] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Unless otherwise defined herein, all technical and scientific terms used in the specific embodiments of the present invention are intended to have the same meaning as commonly understood by one of ordinary skill in the art. Although the following terms are believed to be well understood by those of ordinary skill in the art, the following definitions are set forth to better explain the present invention.

[0036] As used in the present invention, the terms "comprising", "including", "having", "containing" or "involving" are inclusive or open-ended and do not exclude other unrecited elements or method steps. The term "consisting of" is considered a preferred embodiment of the term "comprising". If a group is defined hereinafter as including at least a certain number of embodiments, this should also be understood to disclose a group preferably consisting only of these embodiments.

[0037] The indefinite or definite articles used in reference to singular form nouns, such as "a" or "an", "the", include the plural forms of such nouns.

[0038] The term "about" in the present invention means an accuracy range that can still guarantee the technical effect of the feature understood by those of ordinary skill in the art. This term generally means ±10% deviation from the indicated value, preferably ±5%.

[0039] In addition, the terms first, second, third, (a), (b), (c) and the like in the specification and claims are used to distinguish similar elements and are not necessarily descriptive of an order or temporal sequence. It should be understood that the terms so applied are interchangeable under appropriate circumstances, and the embodiments described in the present invention can be implemented in an order different from that described or illustrated in the present invention.

[0040] The following is provided only to assist in understanding the present invention. These definitions should not be construed as having a scope less than that understood by those of ordinary skill in the art.

[0041] The technical solutions of the present invention will be further described in detail below in conjunction with the specific embodiments, but this does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0042] This embodiment provides a positive electrode hybrid material for a sodium ion battery, comprising:

[0043] a binder and a conductive additive, and an active material for a sodium ion battery;

[0044] wherein, the binder is SEBS rubber.

[0045] It should be noted that SEBS (Styrene Ethylene Butylene Styrene, hydrogenated styrene-butadiene block copolymer) is a linear triblock copolymer with polystyrene as the end segment and ethylene-butene copolymer obtained by hydrogenating polybutadiene as the middle elastic block. SEBS does not contain unsaturated double bonds, so it has good stability and aging resistance. SEBS has excellent aging resistance, has both plasticity and high elasticity, and can be processed and used without vulcanization.

[0046] As mentioned above, there are various types of SEBS rubbers, which have good alkali resistance.

[0047] In the positive electrode hybrid material of the sodium-ion battery in this embodiment, SEBS rubber is used as a binder to make the positive electrode sheet of the sodium-ion battery. Utilizing the chemical stability of SEBS rubber itself and the stability of the solvent oil during the preparation of the slurry, it has alkali resistance and antioxidant ability. Therefore, the positive electrode hybrid material of the sodium-ion battery has the advantages of good fluidity, good stability, and small viscosity change in the positive electrode slurry prepared with SEBS rubber binder; it avoids the defect that in the positive electrode slurry prepared with the existing positive electrode hybrid material of the sodium-ion battery, the PVDF binder easily reacts with the strong alkaline substances on the surface of the sodium-ion battery material, resulting in the denaturation and failure of the positive electrode slurry.

[0048] Furthermore, the SEBS rubber includes one or a combination of two of unmodified SEBS or maleic acid-modified SEBS rubber.

[0049] In a preferred embodiment, the SEBS rubber is maleic acid-modified SEBS rubber.

[0050] As mentioned above, in this embodiment, maleic acid-modified SEBS rubber is used. Since in maleic acid-modified SEBS rubber, maleic anhydride-grafted SEBS can endow SEBS with polar and reactive groups, increasing the binding between the two-phase materials and generating chemical bonds, thus achieving a better binding effect.

[0051] Furthermore, the weight ratio of SEBS rubber in the positive electrode hybrid material of the sodium-ion battery is 0.1% - 5%;

[0052] Furthermore, the weight ratio of SEBS rubber in the positive electrode hybrid material of the sodium-ion battery is 1.0 - 3.5%.

[0053] Furthermore, the active material of the sodium-ion battery includes one of layered oxides, phosphate compounds, and Prussian compounds;

[0054] Among them, the layered oxide includes one or more of nickel-iron-manganese-sodium layered oxide, copper-containing nickel-iron-manganese-sodium layered oxide, and iron-manganese-sodium layered oxide;

[0055] Among them, the phosphate compound includes one or more of sodium iron phosphate, sodium vanadium phosphate, sodium fluorovanadium phosphate, sodium manganese phosphate, and sodium manganese iron phosphate;

[0056] Preferably, the sodium-ion battery active material is nickel-iron-manganese-sodium layered oxide or sodium fluorovanadium phosphate.

[0057] As described above, through experiments, it can be found that SEBS rubber currently has better adaptability in the two systems of nickel-iron-manganese-sodium layered oxide or sodium fluorovanadium phosphate.

[0058] Furthermore, the conductive additive includes one or more combinations of conductive carbon black, conductive graphite, conductive carbon nanotubes, and conductive graphene;

[0059] Furthermore, the conductive additive is conductive carbon black.

[0060] As described above, using conductive carbon black as the conductive additive is because conductive carbon black has less usage amount but better ionic and electronic conductivity. Because conductive carbon black has a larger specific surface area, it is beneficial to the adsorption of the electrolyte and thus improves the ionic conductivity. In addition, the primary carbon particles agglomerate to form a branched chain structure, which can form a chain-like conductive structure with the active material, helping to improve the electronic conductivity of the material.

[0061] Furthermore, the weight ratio of the conductive additive after deducting the weight of the current collector aluminum foil is 0.1% - 5%.

[0062] Furthermore, the weight ratio of the conductive additive after deducting the weight of the current collector aluminum foil is 1.5 - 3.5%.

[0063] In addition, this embodiment also provides a positive electrode sheet of a sodium-ion battery, including the positive electrode hybrid material of the sodium-ion battery as described above, and a current collector aluminum foil.

[0064] In addition, this embodiment also provides a positive electrode paste of a sodium-ion battery, including the positive electrode hybrid material of the sodium-ion battery as described above, and a solvent oil.

[0065] As described above, the solvent oil is a solvent used to dissolve SEBS rubber and is one of the five major categories of petroleum products. The uses of solvent oil include: coating solvent oil (commonly known as paint solvent oil), edible oil, printing ink, leather, pesticide, insecticide, rubber, cosmetics, fragrance, medicine, solvent oil for electronic components, etc. Among them, after SEBS rubber is completely dissolved in the solvent oil, it can be used as the positive electrode paste of sodium ions.

[0066] Further, the solvent naphtha has an initial boiling point greater than 100 °C and a final boiling point less than 250 °C, and may or may not contain aromatic hydrocarbons.

[0067] As described above, the solvent naphtha needs to meet the conditions: the initial boiling point > 100 °C, the final boiling point < 250 °C, and it can contain or not contain aromatic hydrocarbons. By controlling the levels of the initial boiling point and the final boiling point, it is of great significance to the stability of the slurry and the durability of the operation; it has a decisive impact on the temperature and rate during the coating heating and baking process.

[0068] Further, the solvent naphtha is solvent naphtha of grade D85;

[0069] Further, the solid content in the positive electrode slurry is 35% - 75%.

[0070] In addition, this embodiment also provides a method for preparing the positive electrode slurry of the sodium ion battery as described above, including:

[0071] Preparing a first mixture after mixing the binder and the solvent naphtha;

[0072] Taking the conductive additive and adding it to the first mixture to obtain a second mixture;

[0073] Taking the active material of the sodium ion battery and adding it to the second mixture to obtain a third mixture;

[0074] Taking the solvent naphtha and adding it to the third mixture, and adjusting the solid content of the slurry to 35% - 75%, thus obtaining the positive electrode slurry of the sodium ion battery.

[0075] Further, after taking the solvent naphtha and adding it to the third mixture, adjusting the solid content of the slurry to 35% - 75%, and thus obtaining the positive electrode slurry of the sodium ion battery, it further includes:

[0076] Taking the positive electrode slurry of the sodium ion battery and coating it on the current collector aluminum foil on a coater, and after rolling, the positive electrode plate of the sodium ion battery is obtained.

[0077] As described above, by adding solvent naphtha to dissolve the SEBS rubber in the positive electrode mixture material, and further adjusting the solid content to 35% - 75% after adding the solvent naphtha, the final product, the positive electrode slurry of the sodium ion battery, is obtained. After coating the positive electrode slurry of the sodium ion battery on the current collector aluminum foil and performing rolling, the positive electrode plate of the sodium ion battery is obtained.

[0078] The present invention will be further described below through specific embodiments. However, it should be understood that these embodiments are only used for more detailed description and should not be construed as limiting the present invention in any form.

[0079] Embodiment:

[0080] Table 1. Preparation parameters in Examples 1-10

[0081]

[0082]

[0083] Example 1

[0084] (1) Prepare the first mixture according to the corresponding preparation parameters in Table 1;

[0085] (2) Take 30 g of conductive carbon black and add it to the first mixture, and stir and disperse evenly to obtain the second mixture;

[0086] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, and stir and disperse and mix evenly to obtain the third mixture;

[0087] (4) Take the solvent oil D85:D25 = 2:1 ratio and mix it into the third mixture, and adjust the solid content of the slurry to 35%-75% to obtain the positive electrode slurry of the sodium-ion battery.

[0088] (5) Take the above positive electrode slurry for coating and rolling to obtain the positive electrode sheet of the sodium-ion battery.

[0089] Example 2

[0090] (1) Prepare the first mixture according to the corresponding preparation parameters in Table 1;

[0091] (2) Take 30 g of conductive carbon black and add it to the first mixture, and stir and disperse evenly to obtain the second mixture;

[0092] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, and stir and disperse and mix evenly to obtain the third mixture;

[0093] (4) Take the solvent oil D25 and mix it into the third mixture, and adjust the solid content of the slurry to 35%-75% to obtain the positive electrode slurry of the sodium-ion battery.

[0094] (5) Take the above positive electrode slurry for coating and rolling to obtain the positive electrode sheet of the sodium-ion battery.

[0095] Example 3

[0096] (1) Prepare the first mixture according to the corresponding preparation parameters in Table 1;

[0097] (2) Take 30 g of conductive carbon black and add it to the first mixture, and stir and disperse evenly to obtain the second mixture;

[0098] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse to mix evenly to obtain a third mixture;

[0099] (4) Take the solvent oil D85 and add it to the third mixture, adjust the solid content of the slurry to 35%-75%, and thus obtain the positive electrode slurry for the sodium-ion battery.

[0100] (5) Take the above positive electrode slurry for coating and roll pressing to obtain the positive electrode sheet for the sodium-ion battery.

[0101] Example 4

[0102] (1) Prepare a first mixture according to the corresponding preparation parameters in Table 1;

[0103] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0104] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse to mix evenly to obtain a third mixture;

[0105] (4) Take the solvent oil D85:D25 in a ratio of 2:1 and add it to the third mixture, adjust the solid content of the slurry to 35%-75%, and thus obtain the positive electrode slurry for the sodium-ion battery.

[0106] (5) Take the above positive electrode slurry for coating and roll pressing to obtain the positive electrode sheet for the sodium-ion battery.

[0107] Example 5

[0108] (1) Prepare a first mixture according to the corresponding preparation parameters in Table 1;

[0109] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0110] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse to mix evenly to obtain a third mixture;

[0111] (4) Take the solvent oil D85:D25 in a ratio of 2:1 and add it to the third mixture, adjust the solid content of the slurry to 35%-75%, and thus obtain the positive electrode slurry for the sodium-ion battery.

[0112] (5) Take the above positive electrode slurry for coating and roll pressing to obtain the positive electrode sheet for the sodium-ion battery.

[0113] Example 6

[0114] (1) Prepare a first mixture according to the corresponding preparation parameters in Table 1;

[0115] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0116] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse and mix evenly to obtain a third mixture;

[0117] (4) Take the solvent oil D85:D25 = 2:1 in proportion and add it to the third mixture, adjust the solid content of the slurry to 35%-75%, and then obtain the positive electrode slurry for the sodium-ion battery.

[0118] (5) Take the above positive electrode slurry for coating and roll pressing to obtain the positive electrode sheet for the sodium-ion battery.

[0119] Example 7

[0120] ((1) Prepare the first mixture according to the corresponding preparation parameters in Table 1;

[0121] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0122] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse and mix evenly to obtain a third mixture;

[0123] (4) Take the solvent oil D85:D25 = 2:1 in proportion and add it to the third mixture, adjust the solid content of the slurry to 35%-75%, and then obtain the positive electrode slurry for the sodium-ion battery.

[0124] (5) Take the above positive electrode slurry for coating and roll pressing to obtain the positive electrode sheet for the sodium-ion battery.

[0125] Example 8

[0126] According to the corresponding preparation parameters in Table 1, but replace the solvent therein with trichloroethylene.

[0127] (1) Prepare the first mixture according to the corresponding preparation parameters in Table 1;

[0128] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0129] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse and mix evenly to obtain a third mixture;

[0130] (4) Take the solvent trichloroethylene and add it to the third mixture, adjust the solid content of the slurry to 35%-75%, and then obtain the positive electrode slurry for the sodium-ion battery.

[0131] (5) Apply the above positive electrode slurry by coating and roll pressing to obtain a positive electrode sheet for a sodium-ion battery.

[0132] Example 9

[0133] According to the corresponding preparation parameters in Table 1. (1) Add 30 g of PVDF to 420 g of NMP, stir to dissolve and then mix evenly to obtain a first mixture;

[0134] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0135] (3) Take 940 g of nickel-iron-manganese-sodium layered oxide and add it to the second mixture, stir and disperse and mix evenly to obtain a third mixture;

[0136] (4) Take the solvent NMP and add it to the third mixture, adjust the solid content of the slurry to 35% - 75%, and thus obtain the positive electrode slurry for the sodium-ion battery.

[0137] (5) Apply the above positive electrode slurry by coating and roll pressing to obtain a positive electrode sheet for a sodium-ion battery.

[0138] Example 10

[0139] (1) Prepare a first mixture according to the corresponding preparation parameters in Table 1;

[0140] (2) Take 30 g of conductive carbon black and add it to the first mixture, stir and disperse evenly to obtain a second mixture;

[0141] (3) Take 940 g of sodium vanadium fluorophosphate and add it to the second mixture, stir and disperse and mix evenly to obtain a third mixture;

[0142] (4) Take the solvent oil D85:D25 = 2:1 in a mixed ratio and add it to the third mixture, adjust the solid content of the slurry to 35% - 75%, and thus obtain the positive electrode slurry for the sodium-ion battery.

[0143] (5) Apply the above positive electrode slurry by coating and roll pressing to obtain a positive electrode sheet for a sodium-ion battery.

[0144] Horizontal evaluation:

[0145] Example Example Features Effect 1 The method in this patent The slurry has good fluidity, does not delaminate, does not agglomerate, and does not become jelly-like 2 Using only D25 Low boiling point and too strong volatility, the slurry is unstable 3 Using only D85 Low boiling point and too strong volatility, the slurry is unstable 4 Using only 1660 After the slurry is dried, it is not sticky enough and is not easy to stick to the aluminum foil 5 Using only 1924 After the slurry is dried, it is not sticky enough and is not easy to stick to the aluminum foil 6 Dissolved at room temperature Difficult to dissolve, not completely dissolved, and there are small particle agglomerations in the slurry 7 Low amount of SEBS The slurry will settle, that is, delaminate 8 Using trichloroethylene as a solvent The slurry is toxic 9 Using PVDF as a binder The slurry becomes jelly-like and cannot be coated 10 The method in this patent The slurry has good fluidity, does not delaminate, does not agglomerate, and does not become jelly-like

[0146] It can be directly obtained from the horizontal evaluation experiment that using only one of the binder solvents or using only one of the SEBS rubbers as the binder solute cannot achieve the effect of no delamination and no agglomeration, and it is not stable.

[0147] When dissolving SEBS rubber at room temperature, it is difficult to dissolve completely, and there are small particle agglomerations in the slurry. Compared with other existing conventional methods, the positive electrode slurry of the sodium-ion battery prepared by the preparation method provided in this embodiment has alkali resistance and antioxidant ability due to the positive electrode mixture composed of SEBS rubber dissolved in solvent oil and the characteristics of the mixture formed by SEBS rubber and its dissolution solvent after dissolution. The slurry has good fluidity, does not delaminate, does not agglomerate, and does not become jelly-like, avoiding the defect that the PVDF binder in the existing sodium-ion battery easily reacts with the strong alkali on the surface of the sodium-ion battery material and becomes denatured and ineffective.

[0148] The above are the preferred embodiments and corresponding examples of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, including but not limited to adjustments of proportions, processes, and dosages, and these all fall within the protection scope of the present invention. The above are the preferred embodiments and corresponding examples of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made, including but not limited to adjustments of proportions, processes, and dosages, and these all fall within the protection scope of the present invention.

Claims

1. A positive electrode slurry for a sodium-ion battery, characterized in that, Comprising: A positive electrode hybrid material for a sodium-ion battery, and a solvent oil; The positive electrode hybrid material for a sodium-ion battery comprises a binder, a conductive additive, and an active material for a sodium-ion battery; Wherein, the binder is SEBS rubber; the SEBS rubber is SEBS rubber of grade 1924 and SEBS rubber of grade 1660; The solvent oil is solvent oil of grade D85 and solvent oil of grade D25; and the mass ratio of the solvent oil of grade D85 to the solvent oil of grade D25 is 2:1; The weight percentage of the SEBS rubber in the positive electrode hybrid material for a sodium-ion battery is 0.1% - 5%; the solid content in the positive electrode slurry for a sodium-ion battery is 35% - 75%.

2. The positive electrode slurry for a sodium-ion battery according to claim 1, characterized in that, The weight percentage of the SEBS rubber in the positive electrode hybrid material for a sodium-ion battery is 1.0% - 3.5%.

3. The positive electrode slurry for a sodium-ion battery according to claim 1, characterized in that, The active material for a sodium-ion battery includes one of layered oxides, phosphate compounds, and Prussian compounds.

4. The positive electrode slurry for a sodium-ion battery according to claim 3, characterized in that, The layered oxide includes one or more of nickel-iron-manganese-sodium layered oxide, copper-containing nickel-iron-manganese-sodium layered oxide, and iron-manganese-sodium layered oxide.

5. The positive electrode slurry for a sodium-ion battery according to claim 3, characterized in that, The phosphate compound includes one or more of sodium iron phosphate, sodium vanadium phosphate, sodium fluorovanadate phosphate, sodium manganese phosphate, and sodium manganese iron phosphate.

6. The positive electrode slurry for a sodium-ion battery according to claim 3, characterized in that, The active material for a sodium-ion battery is nickel-iron-manganese-sodium layered oxide or sodium fluorovanadate phosphate.

7. The positive electrode slurry for a sodium-ion battery according to claim 1, characterized in that, The conductive additive includes one or more combinations of conductive carbon black, conductive graphite, conductive carbon nanotubes, and conductive graphene.

8. The positive electrode slurry for a sodium-ion battery according to claim 7, characterized in that, The conductive additive is conductive carbon black.

9. The positive electrode slurry for a sodium-ion battery according to claim 7, characterized in that, The weight percentage of the conductive additive in the positive electrode hybrid material for a sodium-ion battery is 0.1% - 5%.

10. The positive electrode slurry for a sodium-ion battery according to claim 7, characterized in that, The weight percentage of the conductive additive in the positive electrode hybrid material for a sodium-ion battery is 1.5% - 3.5%.

11. A positive electrode plate for a sodium-ion battery, characterized in that, Comprising the positive electrode hybrid material for a sodium-ion battery as described in any one of claims 1 - 10, and a current collector aluminum foil.

12. The preparation method of the positive electrode slurry for a sodium-ion battery according to any one of claims 1-10, characterized in that, Comprising: Preparing a first mixture after mixing the binder and the solvent oil; Taking the conductive additive and adding it to the first mixture to obtain a second mixture; Taking the active material for a sodium-ion battery and adding it to the second mixture to obtain a third mixture; Taking the solvent oil and adding it to the third mixture, and adjusting the solid content of the slurry to 35% - 75% to obtain the positive electrode slurry for a sodium-ion battery.

13. The preparation method of the positive electrode slurry for a sodium-ion battery according to claim 12, characterized in that, After taking the solvent oil and adding it to the third mixture, and adjusting the solid content of the slurry to 35% - 75% to obtain the positive electrode slurry for a sodium-ion battery, it further includes: Taking the positive electrode slurry for a sodium-ion battery and coating it on a current collector aluminum foil on a coater, and after rolling, obtaining a positive electrode plate for a sodium-ion battery.

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