Silicon-doped sodium-ion battery positive electrode material and preparation method thereof, sodium-ion battery and electric equipment

Abstract

The invention relates to the field of sodium-ion battery positive electrode materials, and discloses a silicon-doped sodium-ion battery positive electrode material and a preparation method thereof, a sodium-ion battery and electric equipment. The mass of the silicon-doped sodium-ion battery positive electrode material is taken as a reference, the doping amount of a silicon element in the silicon-doped sodium-ion battery positive electrode material is T, the doping amount T of the silicon element and the numerical value d50 of the particle size D50 of the positive electrode material meet a relational expression as shown in a formula (I): d50 = m1T + n1 (I), m1 = 0.8-1, n1 = 4500-5500, T is more than 0 and less than or equal to 4000 ppm, and the unit of D50 is nm. When the silicon-doped sodium-ion battery positive electrode material provided by the invention is applied to a sodium-ion battery, the obtained sodium-ion battery has excellent capacity, rate capability and cycle performance.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery cathode material technology, specifically to silicon-doped sodium-ion battery cathode materials and their preparation methods, sodium-ion batteries, and electrical equipment. Background Technology

[0002] In recent years, sodium-ion battery cathode materials have become a research hotspot due to their high theoretical specific capacity and low cost. Among the various series of sodium-ion battery cathode materials currently being studied, layered transition metal oxide sodium storage materials have the advantages of high theoretical specific capacity, excellent charge-discharge performance, and simple synthesis process, and are considered to have good application prospects. However, the practical application of layered transition metal oxide sodium storage materials is still limited by the following problems: the O3 phase structure is prone to irreversible phase transition, resulting in poor structural stability; the slow sodium ion diffusion rate leads to poor rate performance; the volumetric energy density is low; and there are many side reactions. In order to improve the performance of layered cathode materials, the existing technology mainly adopts the strategy of metal cation doping to suppress phase transition. However, single-element doping cannot completely solve the problems existing in cathode materials. Moreover, some elements are toxic and expensive, which hinders their large-scale production and application. In addition, there is no clear correlation between the doping content of these elements and the material physical parameters (compacted density, particle size), making it difficult to guide industrial production.

[0003] Therefore, there is an urgent need in this field to develop a cathode material that can improve cycle and rate performance in order to prepare sodium-ion batteries with long cycle stability and high rate performance. Summary of the Invention

[0004] The purpose of this invention is to provide a sodium-ion battery cathode material and its preparation method, a sodium-ion battery and related electrical equipment, aiming to solve at least one of the aforementioned technical problems in the prior art.

[0005] To achieve the above objectives, a first aspect of the present invention provides a silicon-doped sodium-ion battery cathode material, wherein the silicon doping amount in the silicon-doped sodium-ion battery cathode material is T, based on the mass of the silicon-doped sodium-ion battery cathode material, and the silicon doping amount T and the particle size D50 of the cathode material satisfy the relationship shown in equation (I): d50=m1T+n1 (I), where m1=0.8~1, n1=4500~5500, 0<T≤4000ppm, and the unit of D50 is nm.

[0006] Preferably, the silicon doping amount T and the compaction density PD of the sodium-ion battery cathode material satisfy the relationship shown in equation (II): pd = (m²T + n²) / 1000 (II), where m² = 0.04~0.06, n² = 3100~3200, and the unit of PD is g / cm³. 3.

[0007] Preferably, the silicon-doped sodium-ion battery cathode material is selected from layered oxide cathode materials. Optionally, the layered oxide cathode material is selected from cathode materials containing nickel and manganese. Optionally, the chemical formula of the layered oxide cathode material is Na. x Ni a1 Fe b1 Mn c1 Me d1 Si y O2; Where x = 0.9~1.1, a1 = 0.2~0.4, b1 = 0~0.34, c1 = 0.3~0.45, d1 = 0~0.2; Me is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr.

[0008] Preferably, in the formula (I), m1 = 0.85~0.95.

[0009] Preferably, in the formula (I), n1 = 4600~5200.

[0010] According to a preferred embodiment, the silicon-doped sodium-ion battery cathode material satisfies at least one of the following conditions: A. In the above formula (II), m2 = 0.045~0.055; B. In the above formula (II), n2 = 3125~3175; C. The specific surface area (BET) of the silicon-doped sodium-ion battery cathode material is 0.6~1.5 m². 2 / g, optionally, the BET is 0.6~1m 2 / g; D. The silicon-doped sodium-ion battery cathode material is an O3 phase cathode material; E. The residual alkali on the surface of the silicon-doped sodium-ion battery cathode material is less than 10,000 ppm.

[0011] A second aspect of the present invention provides a method for preparing a silicon-doped sodium-ion battery cathode material as described in the first aspect, the method comprising the following steps: (1) Mix the raw materials containing sodium-ion battery cathode material precursor, sodium source and silicon source to obtain a mixture; (2) The mixture is subjected to preheating and calcination treatment in air atmosphere to obtain the silicon-doped sodium-ion battery cathode material.

[0012] Preferably, the preparation method satisfies at least one of the following conditions: a. In step (1), the sodium-ion battery cathode material precursor is selected from at least one of hydroxide precursor, carbonate precursor and oxide precursor; b. In step (1), the sodium-ion battery cathode material precursor contains nickel and manganese elements. Optionally, the sodium-ion battery cathode material precursor also contains iron elements. Optionally, the raw material also contains M1 source, wherein M1 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr. c. In step (1), the sodium-ion battery cathode material precursor contains nickel and manganese elements. Optionally, the sodium-ion battery cathode material precursor also contains iron elements. Optionally, the sodium-ion battery cathode material precursor also contains M2 elements, wherein M2 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr. d. In step (1), the molar ratio of the metal element in the sodium-ion battery cathode material precursor to the sodium element in the sodium source is 1:0.9-1.1; e. In step (1), the sodium source is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium oxalate, sodium acetate, and sodium citrate; f. In step (1), the silicon source is selected from silicon dioxide; g. In step (1), the mixing conditions include: a rotation speed of 18,000-23,000 rpm and a time of 1.5-2.5 min; h. In step (2), the preheating conditions include: a temperature of 280-320℃ and a time of 20-40min; i. In step (2), the calcination conditions include a temperature of 900-1030℃.

[0013] Preferably, the preparation method satisfies at least one of the following conditions: ① M1 is different from M2; ② The chemical formula of the sodium-ion battery cathode material precursor is Ni a2 Fe b2 Mn c2 M2 d2 (OH)2 or Ni a2 Fe b2 Mn c2 M2 d2 O, where a2=0.2~0.4, b2=0~0.34, c2=0.3~0.45, d2=0~0.2, and M2 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr; ③ In step (2), the calcination treatment conditions also include: the heating rate V1 is 1-2℃ / min, and the holding time T1 is 10-14h.

[0014] A third aspect of the present invention provides a sodium-ion battery, the sodium-ion battery comprising the silicon-doped sodium-ion battery cathode material as described in the first aspect or the silicon-doped sodium-ion battery cathode material prepared by the preparation method described in the second aspect.

[0015] A fourth aspect of the present invention provides an electrical device comprising a sodium-ion battery as described in the third aspect.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages: The silicon doping amount T in the silicon-doped sodium-ion battery cathode material provided by this invention, when satisfying the relationship between the cathode material's particle size D50 and the amount of silicon (as shown in equation (I), not only increases the c-axis of the cathode material and the interlayer spacing of the sodium layers, improving the battery's initial efficiency and rate performance, but also facilitates the formation of more stable Si-O, TM-O, and OO bonds, increasing the occupancy rate of Na sites in the more stable unit cell, which aids in the insertion / extraction of sodium ions, thereby improving the battery's cycle performance and rate performance. Furthermore, silicon has a fluxing effect, increasing the particle size of the cathode material, reducing the specific surface area, and decreasing the contact between the cathode material and the electrolyte, thus reducing side reactions and improving the battery's cycle stability.

[0017] The method for preparing silicon-doped sodium-ion battery cathode material provided by this invention is simple, highly operable, and conducive to large-scale production. Attached Figure Description

[0018] Figure 1 This is a SEM image of the silicon-doped sodium-ion battery cathode material provided in Embodiment 1 of the present invention; Figure 2 This is a SEM image of the silicon-doped sodium-ion battery cathode material provided in Embodiment 2 of the present invention; Figure 3 This is a SEM image of the silicon-doped sodium-ion battery cathode material provided in Embodiment 3 of the present invention; Figure 4 This is a SEM image of the silicon-doped sodium-ion battery cathode material provided in Embodiment 4 of the present invention; Figure 5 This is a SEM image of the silicon-doped sodium-ion battery cathode material provided in Embodiment 5 of the present invention; Figure 6 This is a SEM image of the sodium-ion battery cathode material (undoped silicon) provided in Comparative Example 1 of this invention. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] It should be noted that, in all aspects of the present invention, the same components or terms in each aspect are described only once in one aspect and not repeatedly, and those skilled in the art should not understand this as a limitation of the present invention.

[0021] As used in this article: "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0022] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0023] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1–5” is disclosed, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0024] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0025] "Parts by mass" refers to the basic measurement unit representing the mass ratio relationship of multiple components. One part can represent any unit mass, such as 1 g or 2.689 g, etc. If we say that the mass of component A is a parts by mass and the mass of component B is b parts by mass, it means the mass ratio of component A to component B is a:b. Or it means the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiple factor). It should not be misunderstood that, different from the number of parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0026] "And / or" is used to indicate that either one or both of the described situations may occur. For example, A and / or B includes (A and B) and (A or B). It should be clear that descriptions such as "thin and flat" in the present invention specifically refer to the morphological characteristics of the corresponding structure in the precursor of the positive electrode material and should not be understood as specific quantification.

[0027] In the present invention, the particle size D50 and the average particle size have the same meaning, which refers to the particle size corresponding to when the cumulative particle size distribution percentage of the precursor of the positive electrode material reaches 50%.

[0028] As mentioned above, the first aspect of the present invention provides a silicon-doped sodium-ion battery positive electrode material. Based on the mass of the silicon-doped sodium-ion battery positive electrode material, the doping amount of silicon element in the silicon-doped sodium-ion battery positive electrode material is T. The relationship between the doping amount T of the silicon element and the value d50 of the particle size D50 of the positive electrode material satisfies the relationship shown in formula (I): d50 = m1T + n1 (I), where m1 = 0.8 - 1, n1 = 4500 - 5500, 0 < T ≤ 4000 ppm, and the unit of D50 is nm.

[0029] In some embodiments, the particle size D50 of the positive electrode material is 2 - 10 μm, for example, it can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value between 2 - 10 μm.

[0030] In some embodiments, the doping amount T of silicon element in the silicon-doped sodium-ion battery positive electrode material satisfies 0 < T ≤ 4000 ppm; for example, T can be 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 ppm, 1500 ppm, 2000 ppm, 3000 ppm, 4000 ppm or any value between 0 < T ≤ 4000 ppm.

[0031] In some embodiments, in the formula (I), m1 = 0.85 - 0.95; for example, m1 can be 0.85, 0.90, 0.95 or any value between 0.85 - 0.95.

[0032] In some implementations, n1 = 4600~5200 in the formula (I); for example, n1 can be any value between 4600, 4700, 4800, 4900, 5000, 5100, 5200 or 4600~5200.

[0033] In some embodiments, the silicon doping amount T and the compaction density PD of the sodium-ion battery cathode material satisfy the relationship shown in equation (II): pd = (m²T + n²) / 1000 (II), where m² = 0.04~0.06, n² = 3100~3200, and the unit of PD is g / cm³. 3 .

[0034] Test conditions for compaction density (PD): The compaction density tester of Sansi Zongheng UIM 7305 was used. The test method is as follows: Weigh 1g of the material to be tested and place it in a clean mold. The radius of the hole in the mold is 6.5mm. Then place the mold on the pressure plate of the equipment and select the test pressure of 3T for testing.

[0035] In some embodiments, in equation (II), m2 = 0.045 to 0.055; for example, m2 can be any value between 0.045, 0.050, 0.055 or 0.045 to 0.055.

[0036] In some implementations, n2 = 3125~3175 in equation (II); for example, n2 can be any value between 3125, 3130, 3135, 3140, 3145, 3155, 3165, 3170, 3175 or 3125~3175.

[0037] In some embodiments, the compaction density (PD) of the sodium-ion battery cathode material is 3.0-3.5 g / cm³. 3 For example, it can be 3.0 g / cm³. 3 3.1g / cm 3 3.3g / cm 3 3.5g / cm 3 Or 3.0-3.5g / cm 3 The compaction density of the silicon-doped sodium-ion battery cathode material is within any of the aforementioned ranges. Applying it to sodium-ion batteries is beneficial for improving the volumetric energy density of the battery.

[0038] In some embodiments, the silicon-doped sodium-ion battery cathode material is selected from layered oxide cathode materials; Optionally, the layered oxide cathode material is selected from cathode materials containing nickel and manganese. Optionally, the chemical formula of the layered oxide cathode material is Na. x Ni a1 Fe b1 Mn c1 Me d1 Si y O2; wherein, x = 0.9~1.1, a1 = 0.2~0.4, b1 = 0~0.34, c1 = 0.3~0.45, d1 = 0~0.2, and Me is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr.

[0039] In some embodiments, the specific surface area (BET) of the silicon-doped sodium-ion battery cathode material is 0.6~1.5 m². 2 / g, for example, can be 0.6m 2 / g, 0.8m 2 / g, 1.0m 2 / g, 1.1m 2 / g, 1.2m 2 / g, 1.3m 2 / g, 1.4m 2 / g, 1.5m 2 / g or 0.6~1.5m 2 Any value between / g, the present invention may select 0.6~1m 2 / g.

[0040] In some embodiments of the present invention, the specific surface area of ​​the silicon-doped sodium-ion battery cathode material is relatively small (0.6~1.5m²). 2 / g), which can reduce side reactions of the electrolyte and enhance air stability.

[0041] In some embodiments, the silicon-doped sodium-ion battery cathode material is an O3 phase cathode material, and this O3 phase crystal structure helps the battery maintain a high capacity.

[0042] In some embodiments, the residual alkali on the surface of the silicon-doped sodium-ion battery cathode material is less than 10,000 ppm. For example, the residual alkali on the surface of the silicon-doped sodium-ion battery cathode material can be any value between 1,000 ppm, 2,000 ppm, 3,000 ppm, 4,000 ppm, 5,000 ppm, 6,000 ppm, 7,000 ppm, 8,000 ppm, 9,000 ppm or less than 10,000 ppm.

[0043] As mentioned above, a second aspect of the present invention provides a method for preparing a silicon-doped sodium-ion battery cathode material as described in the first aspect, the method comprising the following steps: (1) Mix the raw materials containing sodium-ion battery cathode material precursor, sodium source and silicon source to obtain a mixture; (2) The mixture is subjected to preheating and calcination treatment in air atmosphere to obtain the silicon-doped sodium-ion battery cathode material.

[0044] In some embodiments, in step (1), the sodium-ion battery cathode material precursor is selected from at least one of hydroxide precursors, carbonate precursors and oxide precursors.

[0045] In some embodiments, in step (1), the sodium-ion battery cathode material precursor contains nickel and manganese elements. Optionally, the sodium-ion battery cathode material precursor also contains iron. Optionally, the raw material also contains an M1 source, wherein M1 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr.

[0046] In some embodiments, in step (1), the sodium-ion battery cathode material precursor contains nickel and manganese elements. Optionally, the sodium-ion battery cathode material precursor also contains iron. Optionally, the sodium-ion battery cathode material precursor also contains M2 elements, wherein M2 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr.

[0047] In some implementations, M1 is different from M2.

[0048] In some embodiments, the chemical formula of the sodium-ion battery cathode material precursor is Ni. a2 Fe b2 Mn c2 M2 d2 (OH)2 or Ni a2 Fe b2 Mn c2 M2 d2 O, where a2=0.2~0.4, b2=0~0.34, c2=0.3~0.45, d2=0~0.2, and M2 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr.

[0049] In some embodiments, in step (1), the molar ratio of the metal element in the sodium-ion battery cathode material precursor to the sodium element in the sodium source is 1:0.9-1.1; for example, it can be any value between 1:0.9, 1:0.95, 1:0.97, 1:1, 1:1.03, 1:1.05, 1:1.1 or 1:0.9-1.1.

[0050] In some embodiments, in step (1), the sodium source is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium oxalate, sodium acetate, and sodium citrate.

[0051] In some embodiments, in step (1), the silicon source is selected from silicon dioxide.

[0052] In some embodiments, in step (1), the mixing conditions include: a rotational speed of 18,000-23,000 rpm, for example, any value between 18,000 rpm, 19,000 rpm, 20,000 rpm, 21,000 rpm, 22,000 rpm, 23,000 rpm or 18,000-23,000 rpm; and a time of 1.5-2.5 min, for example, any value between 1.5 min, 2.0 min, 2.5 min or 1.5-2.5 min.

[0053] In some embodiments, in step (2), the preheating conditions include: a temperature of 280-320°C, for example, any value between 280°C, 290°C, 300°C, 310°C, 320°C or 280-320°C; and a time of 20-40 min, for example, any value between 20 min, 25 min, 30 min, 35 min, 40 min or 20-40 min.

[0054] In some embodiments, the calcination conditions in step (2) include a temperature of 900-1030°C, for example, 900°C, 950°C, 980°C, 1000°C, 1030°C or any value between 900-1030°C.

[0055] In some embodiments, the calcination treatment conditions in step (2) further include: the heating rate V1 is 1-2℃ / min, for example, the heating rate V1 can be any value between 1℃ / min, 1.5℃ / min, 2.0℃ / min or 1-2℃ / min; the holding time T1 is 10-14h, for example, it can be any value between 10h, 12h, 14h or 10-14h.

[0056] The preparation method of the silicon-doped sodium-ion battery cathode material of the present invention may also include post-processing methods known in the art, such as cooling, crushing and sieving, so as to obtain the silicon-doped sodium-ion battery cathode material of better quality. The present invention will not elaborate further here, and those skilled in the art should not understand it as a limitation of the present invention.

[0057] As previously described, a third aspect of the present invention provides a sodium-ion battery, the sodium-ion battery comprising the silicon-doped sodium-ion battery cathode material as described in the first aspect or the silicon-doped sodium-ion battery cathode material prepared by the preparation method described in the second aspect.

[0058] As previously described, a fourth aspect of the present invention provides an electrical device comprising a sodium-ion battery as described in the third aspect.

[0059] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the raw materials are all commercially available products.

[0060] Preparation Example 1 Ni, a precursor for preparing sodium-ion battery cathode materials 0.26 Fe 0.33 Mn 0.33 Cu 0.04 Zn 0.04 (OH)2: ①Preparation of metal salt solution: according to Ni 0.26 Fe 0.33 Mn 0.33 Cu 0.04 Zn 0.04 Weigh out the proportions of nickel, manganese, iron, copper and zinc in (OH)2. Weigh out nickel sulfate, ferrous sulfate, manganese sulfate, copper sulfate and zinc sulfate. Dissolve nickel sulfate, ferrous sulfate, manganese sulfate, copper sulfate and zinc sulfate in deionized water to form a metal salt solution with a total metal ion concentration of 2 mol / L. Prepare a 10.8 mol / L sodium hydroxide solution as a precipitant solution and an 11 mol / L ammonia solution as a complexing agent solution. ② In the presence of nitrogen, deionized water, precipitant solution and complexing agent solution are added to the reaction vessel and mixed to obtain a bottom liquid, so that the pH value of the bottom liquid is 10.30 and the mass concentration of ammonia water in the bottom liquid is 3.5g / L; ③ Introduce nitrogen into the reactor and control the oxygen volume content in the gas phase atmosphere to be ≤0.5%. Heat the reaction to 45°C. In the gas phase atmosphere, introduce the metal salt solution, precipitant solution and complexing agent solution into the bottom liquid to carry out the co-precipitation reaction until the preset particle size is reached. Then stop feeding to obtain the co-precipitation reaction product. ④ The coprecipitation reaction product was centrifuged, filtered, washed, and dried to obtain the precursor Ni. 0.26 Fe0 .33 Mn 0.33 Cu 0.04 Zn 0.04 (OH)2.

[0061] Preparation Example 2 Ni, a precursor for preparing sodium-ion battery cathode materials 0.40 Fe 0.20 Mn 0.40 O: ①According to Ni 0.40 Fe 0.20 Mn 0.40The proportions of nickel, manganese, and iron in O are determined by weighing nickel sulfate, ferrous sulfate, and manganese sulfate. These are then dissolved in deionized water to form a metal salt solution with a total metal ion concentration of 2 mol / L. Pure water and a pH adjuster (sodium carbonate with a concentration of 1.1 mol / L) are added to a reactor equipped with a stirrer to obtain mixture I (pH 9.5). Nitrogen gas is then introduced to remove air from mixture I, ensuring that the oxygen volume content in mixture I is <1%. ② At a stirring speed of 320 rpm, the reaction temperature is set to 45℃. Then, the precipitant (sodium carbonate solution with a concentration of 1.1 mol / L) and the metal salt solution are slowly added in parallel. The flow rate of the metal salt solution is 4% / h of the total capacity of the reactor. The flow rate of the precipitant is controlled so that the pH of the reaction system is 7.2. After the preset particle size is reached, the feeding is stopped, and the carbonate compound precipitate is obtained.

[0062] ③ The above precipitate was washed with pure water and centrifuged. The centrifuged material was then sintered (heated to 280℃ and held for 5 hours, then heated to 600℃ and held for 5 hours). The dried material was then removed and sealed for storage. The resulting dried material was pulverized in a grinding mill, and then sieved and demagnetized to obtain the precursor Ni. 0.40 Fe 0.20 Mn 0.40 O.

[0063] Example 1 This embodiment illustrates the preparation of silicon-doped sodium-ion battery cathode material according to the raw material formulation in Table 1 and the following steps: (1) The sodium-ion battery cathode material precursor, sodium source (Na2CO3), and silicon source (SiO2) prepared in Example 1 are mixed to obtain a mixture; Mixing conditions: 20,000 rpm, 2 min; (2) Under an air atmosphere, the mixture is subjected to preheating and calcination in sequence, and the calcined product is then cooled, crushed and sieved in sequence to obtain the silicon-doped sodium ion cathode material; Preheating conditions: temperature 300℃, time 30min; Calcination conditions: Heating to 990℃ at a heating rate of 1℃ / min and holding at that temperature for 12h.

[0064] Examples 2-5 Examples 2-5 were all carried out using a method similar to that of Example 1, except that the silicon doping amount was different, as shown in Table 1. For any parts not listed, the same as in Example 1 were used to prepare a silicon-doped sodium ion cathode material.

[0065] Examples 6-7 Examples 6 and 7 illustrate the preparation of silicon-doped sodium-ion battery cathode materials according to the raw material formulation in Table 1 and the following steps: (1) The sodium-ion battery cathode material precursor Ni prepared in Example 2 was used. 0.40 Fe 0.20 Mn 0.40 The raw materials, including O, sodium source (Na2CO3), silicon source (SiO2), copper oxide, zinc oxide, titanium dioxide, and calcium carbonate, are mixed to obtain a mixture. The mixing conditions are: 20,000 rpm and 2 min. (2) Under an air atmosphere, the mixture is subjected to preheating and calcination in sequence, and the calcined product is then cooled, crushed and sieved in sequence to obtain the silicon-doped sodium ion cathode material; Preheating conditions: temperature 300℃, time 30min; Calcination conditions: Heating to 990℃ at a heating rate of 1℃ / min and holding at that temperature for 12h.

[0066] Comparative Example 1 Comparative Example 1 was carried out using a similar method to Example 1, except that no silicon source was added in this comparative example, as shown in Table 1. For any parts not listed, the same as in Example 1 were used to prepare sodium ion cathode materials.

[0067] Comparative Example 2 Comparative Example 2 was carried out using a similar method to Examples 6 and 7, except that no silicon source was added in this comparative example, as detailed in Table 1.

[0068] Comparative Example 3 Comparative Example 3 was carried out using a similar method to Examples 6-7, except that the raw material formulation was different, as detailed in Table 1. In Comparative Example 3, the amount of silicon source added was calculated based on the mass of the final cathode material and the silicon element content was 6000 ppm.

[0069] Comparative Example 4 Comparative Example 4 was carried out using a similar method to Example 1, except that the raw material formulation was different, as detailed in Table 1. In Comparative Example 4, the amount of silicon source added was calculated based on the mass of the final cathode material and the silicon element content was 8000 ppm.

[0070] Comparative Example 5 Comparative Example 5 was carried out using a similar method to Example 1, except that the raw material formulation was different, as detailed in Table 1. In Comparative Example 5, the amount of silicon source added was calculated based on the mass of the final cathode material and the silicon element content was 10,000 ppm.

[0071] Comparative Example 6 Comparative Example 6 was carried out using a similar method to Example 1, except that the raw material formulation was different (see Table 1 for details), and the calcination conditions were as follows: the temperature was increased to 870°C at a heating rate of 1°C / min and held for 12 hours. In Comparative Example 6, the amount of silicon source added was calculated based on the mass of the final cathode material and the proportion of silicon element was 1000ppm.

[0072] Comparative Example 7 Comparative Example 7 was carried out using a method similar to that of Example 1, except that the raw material formulation was different (see Table 1 for details), and the calcination conditions were as follows: the temperature was increased to 870°C at a heating rate of 1°C / min and held for 12 hours. In Comparative Example 7, the amount of silicon source added was calculated based on the mass of the final cathode material and the proportion of silicon element was 2000ppm.

[0073] Comparative Example 8 Comparative Example 8 was carried out using a method similar to that of Examples 6 and 7, except that the raw material formulation was different (see Table 1 for details), and the calcination conditions were as follows: the temperature was increased to 870°C at a heating rate of 1°C / min and held for 12 hours. In Comparative Example 8, the amount of silicon source added was calculated based on the mass of the final cathode material and the proportion of silicon element was 3000ppm.

[0074] Comparative Example 9 Comparative Example 9 was carried out using a method similar to that of Examples 6 and 7, except that the raw material formulation was different (see Table 1 for details), and the calcination conditions were as follows: the temperature was increased to 870°C at a heating rate of 1°C / min and held for 12 hours. In Comparative Example 8, the amount of silicon source added was calculated based on the mass of the final cathode material and the proportion of silicon element was 4000ppm.

[0075] Table 1. Raw material list for preparing cathode materials in Examples 1-7 and Comparative Examples 1-9

[0076] Test Example 1 The physicochemical data of the cathode material precursors prepared in the aforementioned examples were tested, and the test results are shown in Table 2; specifically: 1. Particle size D50 was tested using a Malvern 3000 laser particle size analyzer, referring to standard GB / T 19077-2016; 2. Compacted density test conditions (refer to standard GB / T 44330-2024): The compacted density tester of Sansi Zongheng UIM 7305 is used. The test method is as follows: Weigh 1g of the material to be tested and place it in a clean mold. The radius of the hole in the mold is 6.5mm. Then place the mold on the pressure plate of the equipment and select the test pressure of 3T for testing.

[0077] 3. Specific surface area (BET) is determined according to GB / T 19587-2017 Gas adsorption BET method for solid substances. 4. The residual alkali content shall be determined in accordance with the standard GB / T 41704-2022.

[0078] Table 2. Parameters of silicon-doped sodium-ion cathode materials prepared in the examples and comparative examples.

[0079] Test Example 2 Preparation of sodium-ion batteries: (1) The above silicon-doped sodium-ion battery positive electrode material, conductive carbon black, and binder PVDF (polyvinylidene fluoride) are mixed in a ratio of 8:1:1 to form a slurry, which is then uniformly coated on an aluminum foil with a length and width of 2cm×1cm to form a positive electrode sheet. (2) Assemble the battery case, positive electrode, negative electrode (sodium metal sheet), separator (glass fiber), spring sheet, gasket, and electrolyte (1 mol / L NaClO4 solution) into a CR2032 button battery in a vacuum glove box.

[0080] The electrochemical performance of the prepared sodium-ion battery was tested using the Blue Electric CT3002A testing system, as follows (1C=150mA / g): ① Capacity test: The prepared coin cell was charged at approximately 25°C with a constant current (C) at a rate of 0.1C until it reached a voltage of 4.0V, and then discharged at a constant current at a rate of 0.1C until it reached a voltage of 2.0V (first cycle). The first coulombic efficiency was calculated (first coulombic efficiency % = 0.1C discharge capacity / 0.1C charge capacity). ② Rate performance test: The prepared coin cells were tested at different rates within a voltage range of 2.0-4.0V at approximately 25℃. The charging rate was 0.1C and the discharging rates were 0.1C, 0.2C, 0.5C, 0.8C and 1C, respectively. The discharge capacity retention rate at 1C was calculated.

[0081] ③ Cyclic performance test: The prepared coin cells were subjected to different rate performance tests at approximately 25°C and within a voltage range of 2.0-4.0V. The cells were charged at 0.1C and discharged at 0.1C for two cycles, charged at 0.2C and discharged at 0.2C for two cycles, and then charged at 1C for 50 cycles. The cycle retention rate after 50 cycles was calculated. The test results are shown in Table 3. Table 3. Electrochemical performance test results of batteries composed of cathode materials from the examples and comparative examples.

[0082] The results above show that when the silicon doping amount T in the provided silicon-doped sodium-ion battery cathode material and the particle size D50 of the cathode material satisfy the relationship shown in the aforementioned formula (I), the corresponding coin cell prepared has better capacity, rate performance and cycle performance.

[0083] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A silicon-doped sodium-ion battery cathode material, characterized in that, Based on the mass of the silicon-doped sodium-ion battery cathode material, the silicon doping amount in the silicon-doped sodium-ion battery cathode material is T. The silicon doping amount T and the particle size D50 of the cathode material satisfy the relationship shown in equation (I): d50=m1T+n1(I) Where m1 = 0.8~1, n1 = 4500~5500, 0 < T ≤ 4000ppm; The unit of D50 is nm.

2. The silicon-doped sodium-ion battery cathode material according to claim 1, characterized in that, The silicon doping amount T and the compaction density PD of the sodium-ion battery cathode material satisfy the relationship shown in equation (II): pd=(m2T+n2) / 1000(II), Where m2 = 0.04~0.06, n2 = 3100~3200; The unit of PD is g / cm³. 3 .

3. The silicon-doped sodium-ion battery cathode material according to claim 1, characterized in that, The silicon-doped sodium-ion battery cathode material is selected from layered oxide cathode materials. Optionally, the layered oxide cathode material is selected from cathode materials containing nickel and manganese. Optionally, the chemical formula of the layered oxide cathode material is Na. x Ni a1 Fe b1 Mn c1 Me d1 Si y O2; Where x = 0.9~1.1, a1 = 0.2~0.4, b1 = 0~0.34, c1 = 0.3~0.45, d1 = 0~0.2; Me is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr.

4. The silicon-doped sodium-ion battery cathode material according to claim 1, characterized in that, In equation (I), m1 = 0.85~0.95; And / or, in the above formula (I), n1 = 4600~5200.

5. The silicon-doped sodium-ion battery cathode material according to claim 2, characterized in that, The silicon-doped sodium-ion battery cathode material satisfies at least one of the following conditions: A. In the above formula (II), m2 = 0.045~0.055; B. In the above formula (II), n2 = 3125~3175; C. The specific surface area (BET) of the silicon-doped sodium-ion battery cathode material is 0.6~1.5 m². 2 / g, optionally, the BET is 0.6~1m 2 / g; D. The silicon-doped sodium-ion battery cathode material is an O3 phase cathode material; E. The residual alkali on the surface of the silicon-doped sodium-ion battery cathode material is less than 10,000 ppm.

6. A method for preparing the silicon-doped sodium-ion battery cathode material according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: The raw materials, including sodium-ion battery cathode material precursor, sodium source and silicon source, are mixed to obtain a mixture; The mixture was subjected to preheating and calcination treatments in an air atmosphere to obtain the silicon-doped sodium-ion battery cathode material.

7. The preparation method according to claim 6, characterized in that, The preparation method satisfies at least one of the following conditions: a. The sodium-ion battery cathode material precursor is selected from at least one of hydroxide precursor, carbonate precursor and oxide precursor; b. The sodium-ion battery cathode material precursor contains nickel and manganese. Optionally, the sodium-ion battery cathode material precursor also contains iron. Optionally, the raw material also contains an M1 source, wherein M1 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr. c. The sodium-ion battery cathode material precursor contains nickel and manganese. Optionally, the sodium-ion battery cathode material precursor also contains iron. Optionally, the sodium-ion battery cathode material precursor also contains M2, wherein M2 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr. d. The molar ratio of the metal element in the sodium-ion battery cathode material precursor to the sodium element in the sodium source is 1:0.9-1.1; e. The sodium source is selected from at least one of sodium carbonate, sodium bicarbonate, sodium hydroxide, sodium oxalate, sodium acetate, and sodium citrate; f. The silicon source is selected from silicon dioxide; g. The mixing conditions include: a rotation speed of 18,000-23,000 rpm and a mixing time of 1.5-2.5 min; h. The preheating conditions include: a temperature of 280-320℃ and a time of 20-40 min; i. The conditions for the calcination treatment include a temperature of 900-1030℃.

8. The preparation method according to claim 7, characterized in that, The preparation method satisfies at least one of the following conditions: ① M1 is different from M2; ② The chemical formula of the sodium-ion battery cathode material precursor is Ni a2 Fe b2 Mn c2 M2 d2 (OH)2 or Ni a2 Fe b2 Mn c2 M2 d2 O, where a2=0.2~0.4, b2=0~0.34, c2=0.3~0.45, d2=0~0.2, and M2 is selected from at least one of Ca, Cu, Zn, Mg, Ga, Al, Ti, and Zr; ③ The calcination treatment conditions also include: a heating rate V1 of 1-2℃ / min and a holding time T1 of 10-14h.

9. A sodium-ion battery, characterized in that, The sodium-ion battery includes the silicon-doped sodium-ion battery cathode material as described in any one of claims 1-5 or the silicon-doped sodium-ion battery cathode material prepared by the preparation method described in any one of claims 6-8.

10. An electrical-related device, characterized in that, The electrical equipment includes the sodium-ion battery as described in claim 9.

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