A sodium-ion battery precursor, a preparation method and application thereof

Abstract

The application discloses a sodium ion battery precursor and a preparation method and application thereof. The sodium ion battery precursor comprises a precursor base body and a zinc hydroxystannate coating layer coated on the surface of the precursor base body. The electrochemical performance of a sodium ion battery positive electrode material prepared by using the sodium ion battery precursor can be obviously improved, and the rate performance and cycle performance of the battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery technology, and relates to a sodium-ion battery precursor, its preparation method, and its application. Background Technology

[0002] Due to the similar physicochemical properties of sodium to lithium and its abundant reserves, sodium-ion batteries are expected to replace lithium-ion batteries and have great application potential in electric motorcycles, low-speed electric vehicles, and large-scale energy storage.

[0003] Among sodium-ion battery cathode materials, layered transition metal oxide cathode materials possess advantages such as compact crystal structure, low cost, and ease of synthesis, making them a promising class of cathode materials. However, during charge and discharge processes, sodium-ion batteries face significant challenges, including severe phase structure transformation, slow diffusion kinetics, and interface degradation.

[0004] To address the above issues, the main methods for modifying sodium-ion batteries are coating and doping. Among them, there are roughly four types of coating materials for sodium-ion battery cathodes: metal oxides, non-metallic element coatings, sodium / lithium fast ion conductors, and organic / conductive polymers.

[0005] CN108987708A discloses a cathode material for sodium-ion batteries. The preparation method includes first preparing a cathode material matrix, and then mixing the cathode material matrix with a zirconium source followed by calcination. This patent improves the specific capacity and cycle stability of the battery by using ZrO2 to coat the cathode material matrix.

[0006] CN110224130A discloses a Prussian blue-based sodium-ion battery cathode material coated with a conductive polymer. The preparation method includes first preparing a Prussian blue analogue, then adding the conductive polymer monomer and the Prussian blue analogue to water, ultrasonically dispersing and stirring to obtain a turbid liquid. While maintaining a certain temperature and stirring, a solution containing an initiator is added to the turbid liquid. After the addition is complete, stirring continues for 6-10 hours. The precipitate is then centrifuged, washed, and dried to obtain the Prussian blue-based sodium-ion battery cathode material coated with a conductive polymer. This patent achieves a core-shell structure with a Prussian blue analogue as the bulk material and a conductive polymer coating on the surface by in-situ polymerization of conductive polymers on the surface of the Prussian blue analogue. This improves the ionic and electronic conductivity of the material, as well as its cycle stability and rate performance.

[0007] CN109449395A discloses a method for preparing a lithium-ion battery cathode material with lithium-ion conductor coating. The method utilizes a sol-gel method and a wet chemical coating method to prepare a pure-phase lithium-ion conductor-coated sodium-ion battery cathode material. Compared to uncoated materials, the prepared lithium-ion conductor-coated sodium-ion battery cathode material exhibits significant improvements in battery performance, including specific capacity and rate capability.

[0008] Although different types of cathode materials for sodium-ion batteries each have their own advantages, they also have their own shortcomings. Further improvements are needed in enhancing the dynamic performance of sodium-ion batteries. Moreover, direct coating on the surface of the cathode material limits performance improvement due to interface issues.

[0009] Therefore, providing a new coating method to improve the kinetic performance of sodium-ion batteries is a technical problem that urgently needs to be solved. Summary of the Invention

[0010] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a sodium-ion battery precursor, its preparation method and application.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] In a first aspect, the present invention provides a sodium-ion battery precursor, the sodium-ion battery precursor comprising a precursor matrix and a zinc hydroxystannate coating layer covering the surface of the precursor matrix.

[0013] This invention provides a novel sodium-ion battery precursor. By coating the surface of the precursor substrate with a zinc hydroxystannate coating layer, the performance of the cathode material prepared using this precursor can be improved. The technical principle is as follows: When preparing cathode materials using the cathode material precursor, sodium addition and calcination are generally required. Because the precursor surface has a zinc hydroxystannate coating layer, on the one hand, after sodium addition and calcination, zinc oxide and tin oxide coating layers can be constructed in situ, acting as a barrier to prevent the cathode material from getting damp, resisting electrolyte / electrolyte corrosion, and inhibiting interfacial reactions. On the other hand, while constructing the zinc oxide and tin oxide coating layers in situ, a sodium-deficient phase is induced near the surface of the coating layer and the cathode material substrate, improving the overall kinetic properties of the material particles, enhancing the electrochemical performance of the battery, and improving the battery's rate performance and cycle performance.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following preferred technical solutions.

[0015] Preferably, based on the total mass of the sodium-ion battery precursor, the content of the zinc hydroxystannate coating layer is 0.05wt% to 5wt%, for example, 0.05wt%, 0.07wt%, 0.08wt%, 0.1wt%, 0.3wt%, 0.6wt%, 0.6wt%, 0.8wt%, 1wt%, 1.2wt%, 1.5wt%, 1.7wt%, 2wt%, 2.3wt%, 2.5wt%, 2.8wt%, 3wt%, 3.3wt%, 3.6wt%, 3.8wt%, 4wt%, 4.2wt%, 4.4wt%, 4.7wt%, or 5wt%.

[0016] Preferably, the precursor matrix has the chemical formula Ni. x Fe a Mn b M y (OH)2, where x+y+a+b=1, 0.05≤y≤0.16, and M includes at least one of Cu, Mg, Ti, V, Cr, Co, Ta, La, Nb, Zr, Al, Sn, Ru, Sr, W and Mo.

[0017] Preferably, x+y=0.33, a=0.33, b=0.33.

[0018] In a second aspect, the present invention provides a method for preparing a sodium-ion battery precursor as described in the first aspect, the method comprising the following steps:

[0019] (1) Dissolve soluble tin salts with alkaline solution to obtain a tin-containing solution;

[0020] (2) Add zinc oxide, water and precursor matrix to the tin-containing solution, heat and react to obtain the sodium-ion battery precursor.

[0021] In the method of the present invention, since tin salts are easily hydrolyzed to form precipitates, dissolving them with an alkaline solution can effectively inhibit hydrolysis.

[0022] Preferably, the alkaline solution in step (1) includes NaOH solution, KOH solution, or a mixed solution of NaOH and KOH.

[0023] Preferably, the concentration of the alkaline solution in step (1) is 2 mol / L to 7 mol / L, for example, 2 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, 5.5 mol / L, 6 mol / L, 6.5 mol / L or 7 mol / L.

[0024] Preferably, the amount of alkaline solution used in step (1) is sufficient to titrate the soluble tin salt until it is colorless and clear.

[0025] Preferably, the soluble tin salt in step (1) includes SnCl4.

[0026] Preferably, the Sn concentration in the tin-containing solution in step (1) is 2 g / L to 10 g / L, such as 2 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L, 7 g / L, 7.5 g / L, 8 g / L, 9 g / L or 10 g / L.

[0027] As a preferred technical solution of the preparation method of sodium-ion battery precursor of the present invention, the particle size D50 of the precursor matrix in step (2) is 4μm to 18μm, for example 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 13μm, 14μm, 14.5μm, 15μm, 16μm, 16.5μm, 17μm or 18μm, etc.

[0028] Preferably, in step (2), the amount of zinc oxide used is 1g to 10g relative to each 1L of tin-containing solution, such as 1g, 2g, 3g, 4g, 5g, 6g, 7g, 8g, 9g or 10g.

[0029] Preferably, in step (2), the amount of water used is 0.5L to 5L relative to each 1L of tin-containing solution, for example, 0.5L, 1L, 1.5L, 2L, 2.5L, 3L, 3.5L, 4L, 4.5L or 5L.

[0030] Preferably, in step (2), the temperature is raised to 70℃~90℃, for example 70℃, 75℃, 80℃, 82℃, 85℃, 88℃ or 90℃.

[0031] Preferably, the reaction in step (2) is carried out at a constant temperature and is accompanied by stirring during the reaction.

[0032] Preferably, the reaction time in step (2) is 4h to 12h, for example, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h.

[0033] Preferably, the reaction described in step (2) is followed by separation, washing with water and drying steps.

[0034] Preferably, the step of post-treatment after washing and before drying includes: adding the washed product to the dispersion, ultrasonically dispersing it, and then performing azeotropic distillation.

[0035] As a preferred technical solution of the method for preparing the sodium-ion battery precursor of the present invention, the method for preparing the precursor matrix in step (2) includes the following steps:

[0036] (a) Prepare a mixed solution A by mixing nickel source, iron source, manganese source and dopant element M source according to the formula amount;

[0037] (b) Add the aforementioned mixed solution A, precipitant solution B and complexing agent solution C to the substrate to carry out a coprecipitation reaction to obtain the aforementioned precursor matrix.

[0038] Preferably, the nickel source, iron source, manganese source and dopant element M source in step (a) are independently selected from at least one of sulfate, chloride or acetate.

[0039] Preferably, the precipitant in the precipitant solution B in step (b) includes at least one of sodium hydroxide and sodium carbonate.

[0040] Preferably, the complexing agent in the complexing agent solution C in step (b) includes at least one of ammonia, sodium oxalate, sodium citrate, and ethylenediaminetetraacetic acid.

[0041] Preferably, the total metal ion concentration in the mixed solution A in step (a) is 80 g / L to 130 g / L, such as 80 g / L, 82 g / L, 85 g / L, 88 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, or 130 g / L.

[0042] Preferably, the base solution in step (b) is prepared by mixing and stirring water, a precipitant solution, and a complexing agent solution. The pH of the base solution is 9 to 11, such as 9, 9.5, 10, 10.5, or 11. The stirring speed is 300 rpm to 650 rpm, such as 300 rpm, 325 rpm, 350 rpm, 370 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, or 650 rpm.

[0043] Preferably, the coprecipitation reaction in step (b) is carried out under the protection of a protective gas.

[0044] Preferably, the protective gas includes high-purity nitrogen.

[0045] Preferably, during the coprecipitation reaction in step (b), the pH is maintained between 8 and 11, such as 8, 8.5, 9, 9.5, 10, 10.5 or 11.

[0046] Preferably, during the coprecipitation reaction in step (b), the temperature is maintained between 30°C and 70°C, for example, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C.

[0047] Preferably, the coprecipitation reaction in step (b) is accompanied by stirring, and the stirring speed is controlled between 150 rpm and 600 rpm, such as 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm.

[0048] Preferably, in step (b), when the co-precipitation reaction proceeds to the point where the particle size of the precursor matrix reaches the preset particle size, the feeding is stopped, the matrix is ​​aged and washed to obtain the precursor matrix.

[0049] Thirdly, the present invention provides a sodium-ion battery cathode material, which is prepared by using the sodium-ion battery precursor described in any one of claims 1-3 as raw material, and then adding sodium and calcining it.

[0050] In one embodiment, the method for preparing the positive electrode material of a sodium-ion battery includes the following steps:

[0051] The sodium-ion battery precursor is combined with sodium salt and then calcined to obtain the sodium-ion battery cathode material.

[0052] In one embodiment, the sodium salt is sodium hydroxide.

[0053] In this invention, the sodium-ion cathode material prepared using the sodium-ion battery precursor provided in the first aspect has a zinc oxide and tin oxide coating layer on its surface. The coating layer and the cathode material substrate have a sodium-deficient phase near the surface, thereby improving the kinetic performance of the cathode material.

[0054] Fourthly, the present invention provides a sodium-ion battery, wherein the sodium-ion battery comprises the sodium-ion battery positive electrode material described in the third aspect.

[0055] The sodium-ion battery of the present invention has improved electrochemical performance, good rate performance and cycle performance due to the use of the above-mentioned sodium-ion battery cathode material.

[0056] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0057] Compared with existing technologies, the present invention has the following beneficial effects:

[0058] This invention provides a sodium-ion battery precursor, which significantly improves the electrochemical performance of sodium-ion battery cathode materials prepared using this precursor. The preparation method of the sodium-ion cathode material is consistent with existing processes, requiring only sodium addition and calcination. After sodium addition and calcination, zinc oxide and tin oxide coatings can be constructed in situ, acting as a barrier to prevent the cathode material from getting damp, resisting electrolyte / electrolyte corrosion, and inhibiting interfacial reactions. Moreover, while constructing the zinc oxide and tin oxide coatings in situ, a sodium-deficient phase is induced near the surface of the coating and the cathode material matrix, improving the kinetic properties of the entire material particles, enhancing the battery's electrochemical performance, and improving the battery's rate performance and cycle performance. Detailed Implementation

[0059] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0060] Example 1

[0061] This embodiment provides a sodium-ion battery precursor, which includes a precursor matrix and a zinc hydroxystannate coating layer covering the surface of the precursor matrix.

[0062] The precursor matrix has the chemical formula Ni. 0.21 Fe 0.33 Mn 0.33 Cu 0.12 (OH)2, based on the total mass of the sodium-ion battery precursor as 100%, contains 2.5 wt% zinc hydroxystannate coating.

[0063] The method for preparing the sodium-ion battery precursor provided in this embodiment includes the following steps:

[0064] Step 1: Mix nickel sulfate, ferrous sulfate, manganese sulfate, and copper sulfate according to Ni 0.21 Fe 0.33 Mn 0.33 Cu 0.1 The molar ratio of each element in (OH)2 is mixed to prepare a mixed metal salt solution with a total metal ion concentration of 110 g / L, and a liquid alkali with a mass fraction of 32% and an ammonia solution with a mass fraction of 15% are prepared.

[0065] Step 2: Add pure water, liquid alkali and ammonia water to the reaction vessel as the base liquid, stir, the pH of the base liquid is 10.5, and the stirring speed is controlled at 400 rpm.

[0066] Step 3: Add the mixed metal salt solution, liquid alkali and ammonia water to the reaction vessel at the same time, and introduce high-purity nitrogen gas to prevent oxidation. Stir continuously during the reaction, maintain the pH between 9 and 10, control the reaction temperature at 45℃, and control the stirring speed at 300 rpm. Stop feeding when the particle D50 grows to 6μm, age and wash to obtain sodium-ion battery precursor matrix.

[0067] Step 4: Titrate a certain amount of SnCl4 solid with 4 mol / L NaOH solution until it is colorless and clear, and prepare a tin-containing solution with a Sn concentration of 7 g / L;

[0068] The 0.5 L tin-containing solution and 3.5 g ZnO solid were added to a 1 L three-necked flask equipped with a stirrer, along with 500 mL of deionized water. The washed sodium-ion battery precursor matrix was then added, and the mixture was heated to 85 °C and stirred at this temperature for 8 h to obtain a white emulsion. After the reaction was complete, the product was filtered and washed with deionized water. The product was then ultrasonically dispersed in a round-bottom flask using n-butanol as a dispersant for 2 h, followed by azeotropic distillation at 95 °C. The distilled product was then removed and vacuum dried at 60 °C for 8 h to obtain a sodium-ion battery precursor coated with zinc hydroxystannate.

[0069] Example 2

[0070] This embodiment provides a sodium-ion battery precursor, which includes a precursor matrix and a zinc hydroxystannate coating layer covering the surface of the precursor matrix.

[0071] The precursor matrix has the chemical formula Ni. 0.18 Fe 0.33 Mn 0.33 Mg 0.15 (OH)2, with the total mass of the sodium-ion battery precursor being 100%, contains 5 wt% zinc hydroxystannate coating.

[0072] The method for preparing the sodium-ion battery precursor provided in this embodiment includes the following steps:

[0073] Step 1: Mix nickel nitrate, ferrous chloride, manganese nitrate, and magnesium sulfate according to Ni 0.18 Fe 0.33 Mn 0.33 Mg 0.15 The molar ratio of each element in (OH)2 is mixed to prepare a mixed metal salt solution with a total metal ion concentration of 100 g / L, and a liquid alkali with a mass fraction of 32% and an ammonia solution with a mass fraction of 15% are prepared.

[0074] Step 2: Add pure water, liquid alkali and ammonia water to the reaction vessel as the base liquid, stir, the pH of the base liquid is 9.5, and the stirring speed is controlled at 500 rpm;

[0075] Step 3: Add the mixed metal salt solution, liquid alkali and ammonia water to the reaction vessel at the same time, and introduce high-purity nitrogen gas to prevent oxidation. Stir continuously during the reaction, maintain the pH between 8 and 9, control the reaction temperature at 60℃, and control the stirring speed at 550 rpm. Stop feeding when the particle D50 grows to 10 μm, age and wash to obtain sodium-ion battery precursor matrix.

[0076] Step 4: Titrate a certain amount of SnCl4 solid with 2 mol / L NaOH solution until it is colorless and clear, and prepare a tin-containing solution with a Sn concentration of 10 g / L;

[0077] The 0.5 L tin-containing solution and 5 g ZnO solid were added to a 1 L three-necked flask equipped with a stirrer, along with 500 mL of deionized water. The washed sodium-ion battery precursor matrix was then added, and the mixture was heated to 90 °C and stirred at this temperature for 4 h to obtain a white emulsion. After the reaction was complete, the product was filtered and washed with deionized water. The product was then ultrasonically dispersed in a round-bottom flask using n-butanol as a dispersant for 3 h, followed by azeotropic distillation at 92 °C. The distilled product was then removed and vacuum dried at 70 °C for 6 h to obtain a sodium-ion battery precursor coated with zinc hydroxystannate.

[0078] Example 3

[0079] This embodiment provides a sodium-ion battery precursor, which includes a precursor matrix and a zinc hydroxystannate coating layer covering the surface of the precursor matrix.

[0080] The precursor matrix has the chemical formula Ni. 0.28 Fe 0.33 Mn 0.33 Cr 0.05 (OH)2, based on the total mass of the sodium-ion battery precursor as 100%, contains 0.05 wt% zinc hydroxystannate coating.

[0081] The method for preparing the sodium-ion battery precursor provided in this embodiment includes the following steps:

[0082] Step 1: Mix nickel sulfate, ferrous sulfate, manganese acetate, and chromium acetate according to Ni 0.28 Fe 0.33 Mn 0.33 Cr 0.05 The molar ratio of each element in (OH)2 is mixed to prepare a mixed metal salt solution with a total metal ion concentration of 85 g / L, and a liquid alkali with a mass fraction of 32% and an ammonia solution with a mass fraction of 15% are prepared.

[0083] Step 2: Add pure water, liquid alkali and ammonia water to the reaction vessel as the base liquid, stir, the pH of the base liquid is 11, and the stirring speed is controlled at 300 rpm.

[0084] Step 3: Add the mixed metal salt solution, liquid alkali and ammonia water to the reaction vessel at the same time, and introduce high-purity nitrogen gas to prevent oxidation. Stir continuously during the reaction, maintain the pH between 9.5 and 10.5, control the reaction temperature at 70℃, and control the stirring speed at 200 rpm. Stop feeding when the particle D50 reaches 15 μm, age and wash to obtain the sodium-ion battery precursor matrix.

[0085] Step 4: Titrate a certain amount of SnCl4 solid with 7mol / L NaOH solution until it is colorless and clear, and prepare a tin-containing solution with a Sn concentration of 4g / L;

[0086] The above-mentioned 0.5 L tin-containing solution and 2 g ZnO solid were added to a 1 L three-necked flask equipped with a stirrer, and 500 mL of deionized water was added. The washed sodium-ion battery precursor matrix was then added to the flask. The mixture was heated to 70 °C and stirred at a constant temperature for 10 h to obtain a white emulsion. After the reaction was completed, the product was filtered and washed with deionized water. The product was then ultrasonically dispersed in a round-bottom flask with n-butanol as a dispersant for 1 h, followed by azeotropic distillation at 90 °C. The product obtained after distillation was then removed and vacuum dried at 80 °C for 3 h to obtain a sodium-ion battery precursor coated with zinc hydroxystannate.

[0087] Example 4

[0088] This embodiment provides a sodium-ion battery precursor and its preparation method. The difference between the sodium-ion battery precursor and that in Example 1 is that the content of the zinc hydroxystannate coating layer is 0.03 wt%.

[0089] Example 5

[0090] This embodiment provides a sodium-ion battery precursor and its preparation method. The difference between the sodium-ion battery precursor and that in Example 1 is that the content of the zinc hydroxystannate coating layer is 6 wt%.

[0091] Comparative Example 1

[0092] This comparative example provides a sodium-ion battery precursor and its preparation method. The difference from Example 1 is that the preparation method does not include step (4). Therefore, the sodium-ion battery precursor matrix prepared in step (3) is the finished product.

[0093] Application Example 1

[0094] A sodium-ion battery cathode material is provided, and its preparation method includes the following steps:

[0095] Sodium-ion battery precursor (Example 1) was mixed with NaOH at a molar ratio of 1:1.05 and calcined at 900°C for 10 hours to obtain sodium-ion battery cathode material.

[0096] Application Example 2

[0097] A sodium-ion battery cathode material is provided, and its preparation method includes the following steps:

[0098] Sodium-ion battery precursor (Example 1) was mixed with Na2CO3 at a molar ratio of 1:1.03 and calcined at 850°C for 12 hours to obtain sodium-ion battery cathode material.

[0099] Application Example 3

[0100] A sodium-ion battery cathode material is provided, and its preparation method includes the following steps:

[0101] Sodium-ion battery precursor (Example 1) was mixed with Na2CO3 at a molar ratio of 1:1.02 and calcined at 800°C for 15 hours to obtain sodium-ion battery cathode material.

[0102] Application Example 4-5

[0103] A sodium-ion battery cathode material is provided, the difference from Application Example 1 is that the sodium-ion battery precursor of Example 1 is replaced with the sodium-ion battery precursors of Example 4 and Example 5, respectively.

[0104] Application Comparative Example 1

[0105] A sodium-ion battery cathode material is provided, which differs from Application Example 1 in that the sodium-ion battery precursor of Example 1 is replaced with the sodium-ion battery precursor of Comparative Example 1.

[0106] Application Comparative Example 2

[0107] A sodium-ion battery cathode material is provided, and its preparation method includes the following steps:

[0108] Sodium-ion battery precursor matrix Ni was prepared using the same preparation method and conditions as in Example 1. 0.21 Fe 0.33 Mn 0.33 Cu 0.12 (OH)2, the sodium-ion battery precursor matrix is ​​mixed with NaOH at a molar ratio of 1:1.05 and calcined at 900℃ for 10h to obtain the sodium-ion battery cathode material;

[0109] The sodium-ion battery cathode material was mixed with zinc oxide and tin oxide (the content of zinc oxide and tin oxide was the same as in Application Example 1) and sintered at 600°C for 6 hours to obtain a sodium-ion battery cathode material coated with zinc oxide and tin oxide.

[0110] Assemble the battery and conduct performance tests, specifically:

[0111] The battery assembly method is as follows: prepare battery slurry according to the mass ratio of positive electrode material: binder: conductive agent = 75:15:10, uniformly coat the battery slurry on aluminum foil and dry it to prepare positive electrode sheet, use sodium sheet for negative electrode, and assemble into button half cell.

[0112] Electrochemical performance testing:

[0113] Rate performance testing: Electrochemical window is 2.7-4.1V, 0.2C / 2C cycling for 50 cycles, capacity retention is tested.

[0114] Cyclic performance testing: Electrochemical window is 2.7-4.1V, 0.2C / 5C cycling for 50 cycles, capacity retention is tested.

[0115] The test results are shown in Table 1.

[0116] Table 1

[0117]

[0118]

[0119] As shown in Table 1, the present invention can significantly improve the kinetic performance of sodium-ion battery cathode materials by coating the surface of sodium-ion battery precursor with zinc hydroxystannate and using it to prepare sodium-ion battery cathode materials. The rate performance and cycle performance of batteries assembled with this cathode material are greatly improved compared with batteries assembled with precursors without zinc hydroxystannate coating (using Comparative Example 1).

[0120] Meanwhile, a comparison between Application Example 1 and Application Examples 4-5 shows that the preferred content of the zinc hydroxystannate coating layer is 0.05 to 5% wt. If the content of the zinc hydroxystannate coating layer is too low, the cycle performance will deteriorate significantly; if the content of the zinc hydroxystannate coating layer is too high, the diffusion of Na ions will deteriorate, resulting in a significant deterioration in rate performance.

[0121] By comparing Application Example 1 with Application Comparative Example 2, it can be seen that if zinc oxide and tin oxide are directly coated on the cathode material, the kinetic performance cannot be effectively improved, resulting in no significant improvement in rate performance and cycle performance.

[0122] The applicant declares that the detailed method of the present invention is illustrated by the above embodiments, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sodium-ion battery precursor, characterized in that, The sodium-ion battery precursor includes a precursor matrix and a zinc hydroxystannate coating layer covering the surface of the precursor matrix. The precursor matrix has the chemical formula Ni. x Fe a Mn b M y (OH)2, where x+y+a+b=1, 0.05≤y≤0.16, and M includes at least one of Cu, Mg, Ti, V, Cr, Co, Ta, La, Nb, Zr, Al, Sn, Ru, Sr, W and Mo; Based on the total mass of the sodium-ion battery precursor as 100%, the content of the zinc hydroxystannate coating layer is 0.05wt%~5wt%.

2. The sodium-ion battery precursor of claim 1, wherein, The precursor matrix has the chemical formula Ni. x Fe a Mn b M y (OH)2, where x+y+a+b=1, 0.05≤y≤0.16, x+y=0.33, a=0.33, b=0.

33.

3. A method of producing a sodium-ion battery precursor according to claim 1 or 2, characterized in that, The preparation method includes the following steps: (1) Dissolve the soluble tin salt with an alkaline solution to obtain a tin-containing solution; (2) Add zinc oxide, water and precursor matrix to the tin-containing solution, heat and react to obtain the sodium-ion battery precursor.

4. The method for preparing the sodium-ion battery precursor according to claim 3, characterized in that, The alkaline solution in step (1) includes NaOH solution, KOH solution, or a mixed solution of NaOH and KOH.

5. The method for preparing the sodium-ion battery precursor according to claim 3, characterized in that, The concentration of the alkaline solution in step (1) is 2 mol / L to 7 mol / L.

6. The method for preparing the sodium-ion battery precursor according to claim 3, characterized in that, The amount of alkaline solution used in step (1) is sufficient to titrate the soluble tin salt until it is colorless and clear.

7. The method for preparing the sodium-ion battery precursor according to claim 3, characterized in that, The soluble tin salt in step (1) includes SnCl4.

8. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: The Sn concentration in the tin-containing solution in step (1) is 2 g / L to 10 g / L. ​ 9. The method for preparing the sodium-ion battery precursor according to claim 3, characterized in that, The particle size D50 of the precursor matrix in step (2) is 4μm~18μm.

10. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: In step (2), the amount of zinc oxide used is 1g to 10g relative to 1L of tin-containing solution. ​ 11. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: In step (2), the amount of water used is 0.5L to 5L relative to 1L of tin-containing solution. ​ 12. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: In step (2), the temperature is raised to 70℃~90℃. ​ 13. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: The reaction described in step (2) is carried out at a constant temperature and is accompanied by stirring during the reaction. ​ 14. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: The reaction time in step (2) is 4h to 12h. ​ 15. The method of claim 3, wherein the sodium-ion battery precursor is prepared by a process comprising: Step (2) involves separation, washing with water, and drying after the reaction. ​ 16. The method of claim 15, wherein the sodium-ion battery precursor is prepared by a process comprising: The post-treatment step after washing and drying includes: adding the washed product to the dispersion, ultrasonically dispersing it, and then performing azeotropic distillation.

17. The method for preparing the sodium-ion battery precursor according to claim 3, characterized in that, The preparation method of the precursor matrix in step (2) includes the following steps: (a) Prepare a mixed solution A by mixing the nickel source, iron source, manganese source and dopant element M source according to the formula amount; (b) Add the aforementioned mixed solution A, precipitant solution B and complexing agent solution C to the substrate to carry out a coprecipitation reaction to obtain the aforementioned precursor matrix.

18. The method for preparing a sodium-ion battery precursor according to claim 17, characterized in that, The nickel source, iron source, manganese source and dopant element M source in step (a) are independently selected from at least one of sulfate, chloride or acetate.

19. The method for preparing a sodium-ion battery precursor according to claim 17, characterized in that, The precipitant in step (b) precipitant solution B includes at least one of sodium hydroxide and sodium carbonate.

20. The method of claim 17, wherein the sodium-ion battery precursor is prepared by a process comprising: 20 mixing a sodium source and a carbon source to form a mixture; 21 heating the mixture to form a sodium-ion battery precursor; and 22 cooling the sodium-ion battery precursor. 23 The complexing agent in the complexing agent solution C in step (b) includes at least one of ammonia, sodium oxalate, sodium citrate, and ethylenediaminetetraacetic acid.

21. The method of claim 17, wherein the sodium-ion battery precursor is prepared by a process comprising: The total metal ion concentration in the mixed solution A in step (a) is 80 g / L to 130 g / L. ​ 22. The method of claim 17, wherein the sodium-ion battery precursor is prepared by a process comprising: The base solution in step (b) is prepared by mixing and stirring water, a precipitant solution and a complexing agent solution. The pH of the base solution is 9-11, and the stirring speed is 300 rpm-650 rpm. ​ 23. The method for preparing a sodium-ion battery precursor according to claim 17, characterized in that, The coprecipitation reaction described in step (b) is carried out under the protection of a protective gas.

24. The method of claim 23, wherein the sodium-ion battery precursor is prepared by a process comprising: The protective gas includes high-purity nitrogen. ​ 25. The method for preparing a sodium-ion battery precursor according to claim 17, characterized in that, During the coprecipitation reaction described in step (b), the pH is maintained between 8 and 11.

26. The method of claim 17, wherein the sodium-ion battery precursor is prepared by a process comprising: providing a sodium-ion battery precursor comprising a sodium metal anode, a sodium-ion cathode, and an electrolyte; and applying a coating to the sodium-ion battery precursor to form a sodium-ion battery. During the coprecipitation reaction described in step (b), the temperature is maintained between 30°C and 70°C.

27. The method for preparing a sodium-ion battery precursor according to claim 17, characterized in that, The coprecipitation reaction described in step (b) is accompanied by stirring, and the stirring speed is controlled at 150 rpm to 600 rpm.

28. The method of claim 17, wherein the sodium-ion battery precursor is prepared by a method comprising: providing a sodium metal source; providing a sodium-ion battery cathode material; and combining the sodium metal source and the sodium-ion battery cathode material to form the sodium-ion battery precursor. In step (b), when the coprecipitation reaction proceeds to the point where the particle size of the precursor matrix reaches the preset particle size, the feeding is stopped, the matrix is ​​aged and washed to obtain the precursor matrix.

29. A sodium-ion battery cathode material, characterized in that, The sodium-ion battery cathode material is prepared by using the sodium-ion battery precursor described in claim 1 or 2 as raw material, followed by sodium addition and calcination.

30. A sodium-ion battery, characterized in that, The sodium-ion battery includes the sodium-ion battery cathode material as described in claim 29.

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