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

Abstract

The invention relates to the technical field of sodium-ion battery positive electrode materials, and discloses a sodium-ion battery positive electrode material and a preparation method thereof, a sodium-ion battery and electric equipment. The sodium-ion battery positive electrode material comprises a substrate and a coating layer coating at least part of the surface of the substrate, the chemical formula of the substrate is NaxNiaFebMncMdO2, x is greater than or equal to 0.85 and less than or equal to 1.1, a is greater than 0 and less than 1, b is greater than 0 and less than 1, c is greater than 0 and less than 1, d is greater than 0 and less than 0.5, a + b + c + d = 1, and M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn and W; the coating layer comprises metaphosphoric acid metal salt, and metal elements in the metaphosphoric acid metal salt are selected from at least one of Y, La, Al, Li, Na, Ba and Ca. The battery positive electrode material provided by the invention is applied to the sodium-ion battery, so that the sodium-ion battery has good cycling stability and excellent specific capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium ion battery cathode materials, in particular to a sodium ion battery cathode material, a preparation method thereof, a sodium ion battery and an electrical equipment. BACKGROUND

[0002] Sodium ion batteries have become a research hotspot in the field of large-scale energy storage devices and low-speed electric vehicles due to their abundant sodium resources, low price and similar working principle to lithium ion batteries.

[0003] Among sodium ion battery cathode materials, layered transition metal oxides stand out due to their simple synthesis process, low toxicity and large specific surface area. Cobalt-free NFM (nickel-iron-manganese) cathode materials are considered one of the most promising cathode materials for sodium ion batteries due to their high specific capacity, low cost and simple synthesis method. However, due to the low redox potential of Fe, the matrix energy density is low, and the structure degradation during discharge is more serious.

[0004] In order to fully exert the advantages of cobalt-free NFM cathode materials, scholars have made modifications such as metal element doping or substitution, surface modification, ion exchange and multi-phase combination.

[0005] Among them, high-entropy materials have attracted widespread attention. They are characterized by the coexistence of multiple metal elements in a single phase, exhibiting unique conformational entropy structures. The introduction of multiple cations in the transition metal layer can stabilize the crystal structure and greatly reduce the migration of transition metal atoms to the Na layer, i.e. multiple element coordination can better adapt to the local structural changes caused by sodium (de) ionization process. Compared with traditional materials, high-entropy structure materials exhibit better structural stability and cycle stability.

[0006] Compared with room temperature, high-entropy materials exhibit higher entropy values at high temperatures, and their phase transition behavior is more pronounced, i.e. promoting Fe ion disproportionation reaction and dissolution causing lattice distortion, which is more prone to side reactions with electrolyte, thereby affecting the high-temperature cycle stability of the cathode material.

[0007] Therefore, it is of great significance to develop an NFM-based high-entropy material that can maintain good cycle stability and excellent specific capacity at high temperatures. SUMMARY

[0008] The purpose of the present application is to provide a sodium ion battery cathode material, a preparation method thereof, a sodium ion battery and an electrical equipment, aiming to solve at least one of the above technical problems in the prior art.

[0009] To achieve the above purpose, the first aspect of the present application provides a sodium ion battery cathode material, which comprises a matrix and a coating layer coated on at least part of the surface of the matrix.

[0010] The chemical formula of the substrate is Na x Ni a Fe b Mn c M d O2, wherein 0.85≤x≤1.1, 0

[0011] The coating layer comprises a metal metaphosphate salt, and the metal element in the metal metaphosphate salt is selected from at least one of Y, La, Al, Li, Na, Ba, and Ca.

[0012] Preferably, in the chemical formula of the substrate, 0.2≤a≤0.4, 0

[0013] Preferably, the mass of the metal element in the coating layer is 0.1wt%-1wt% based on the total mass of the substrate, and optionally, the mass of the metal element in the coating layer is 0.2wt%-0.5wt%.

[0014] Preferably, the substrate comprises at least one phase structure of P2, O2, P3, or O3, and optionally, the substrate is an O3 phase structure.

[0015] According to a preferred embodiment, the sodium-ion battery cathode material satisfies at least one of the following conditions:

[0016] ①The particle size D50 of the sodium-ion battery cathode material is 4-8μm;

[0017] ②The specific surface area BET of the sodium-ion battery cathode material is 0.3-0.8m 2 / g;

[0018] ③The compaction density of the sodium-ion battery cathode material is 3.0-3.3g / cm 3 ;

[0019] ④The M is selected from at least two of Ti, Mg, Cu, Ca, and Zn;

[0020] ⑤The metal element in the metal metaphosphate salt is selected from at least one of Y, Al, and Li.

[0021] The second aspect of the present application provides a method for preparing the sodium-ion battery cathode material of the first aspect, and the preparation method comprises the following steps:

[0022] mixing the base material and the metal metaphosphate to obtain a mixture;

[0023] sintering the mixture in an oxygen-containing atmosphere to obtain the sodium-ion battery cathode material.

[0024] Preferably, the preparation method satisfies at least one of the following conditions:

[0025] A. the base material is prepared by calcining a mixture I containing a sodium source and a sodium-ion battery cathode material precursor I containing Ni, Fe, Mn, M1 elements in an air atmosphere, and optionally, the mixture I further contains an M2 source, wherein M1 and M2 are each independently selected from at least one of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W, and M1 is different from M2;

[0026] B. the base material is prepared by calcining a mixture II containing a sodium source, a sodium-ion battery cathode material precursor II containing Ni, Fe, Mn, and an M source in an air atmosphere, wherein M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W;

[0027] C. the base material is prepared by calcining a mixture III containing a sodium source, a nickel source, an iron source, a manganese source, and an M source in an air atmosphere, wherein M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W;

[0028] D. the mass fraction of metal elements in the metal metaphosphate is 0.1wt%-1wt%, and optionally 0.2wt%-0.5wt%, based on the total mass of the base material;

[0029] E. the sintering conditions include a temperature of 400-700℃ and a holding time of 5-8h.

[0030] Preferably, the preparation method satisfies at least one of the following conditions:

[0031] (1) the sodium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium oxalate, and sodium nitrate;

[0032] (2) the sodium-ion battery cathode material precursor I is selected from a hydroxide containing Ni, Fe, Mn, M1 elements and / or an oxide containing Ni, Fe, Mn, M1 elements and / or a carbonate containing Ni, Fe, Mn, M1 elements;

[0033] (3) the sodium-ion battery cathode material precursor II is selected from a hydroxide containing Ni elements, Fe elements, Mn elements and / or an oxide containing Ni elements, Fe elements, Mn elements and / or a carbonate containing Ni elements, Fe elements, Mn elements;

[0034] (4) the nickel source is selected from at least one of nickel oxide, nickel sulfate, nickel chloride, nickel hydroxide, nickel nitrate; and / or the iron source is selected from at least one of diiron trioxide, ferriferrous oxide, ferrous sulfate, iron sulfate, ferrous chloride, ferric chloride, ferrous nitrate, ferric nitrate; and / or the manganese source is selected from at least one of manganese oxide, manganese sulfate, manganese chloride, manganese nitrate; and / or the M source is selected from at least one of an oxide of M, a sulfate of M, a chloride of M, a nitrate of M; and / or the M2 source is selected from at least one of an oxide of M2, a sulfate of M2, a chloride of M2, a nitrate of M2;

[0035] (5) the conditions of the calcination treatment I, the calcination treatment II and the calcination treatment III each independently comprise: a temperature of 750-1050℃; and / or a holding time of 10-14h; and / or a heating rate of 1-5℃ / min.

[0036] The third aspect of the present application provides a sodium-ion battery, which comprises the sodium-ion battery cathode material according to the first aspect or the sodium-ion battery cathode material prepared by the preparation method according to the second aspect.

[0037] The fourth aspect of the present application provides an electrical equipment, which comprises the sodium-ion battery according to the third aspect.

[0038] Compared with the prior art, the technical scheme provided by the present application has at least the following advantages:

[0039] The matrix and the coating layer in the sodium-ion battery cathode material provided by the present application cooperate with each other, can prevent the lattice structure from collapsing and micro-cracks from being generated due to the escape of sodium and transition metal ions, and inhibit the interface side reaction, thereby improving the cycle performance of the material; the sodium ion channel inside the metal metaphosphate in the coating layer behaves as a three-dimensional diffusion channel, similar to the NASICON type material, has a preferential de-intercalation site (such as Na2 site) and a low-energy barrier diffusion channel (<0.5eV), and the diffusion path of sodium ions is more inclined to bypass the high-energy potential barrier site in a nonlinear manner rather than a simple linear diffusion, which provides a basis for improving the diffusion and migration rate of sodium ions, thereby improving the discharge efficiency and cycle stability of the sodium-ion battery at room temperature and high temperature.

[0040] The preparation method of the cathode material precursor provided by the present application is simple and has strong operability, and is beneficial to large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is an XRD pattern of the base material prepared in Preparation Example 1 and the sodium-ion battery cathode material prepared in Example 1.

[0042] Figure 2 is an SEM image of the sodium-ion battery cathode material prepared in Example 1. DETAILED DESCRIPTION

[0043] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. Ranges can be expressed in a variety of ways, for example, by using the terms "between" and "from... to...". Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, all subranges beginning with a minimum value equal to or greater than 1 and ending with a maximum value equal to or less than 10, as well as all subranges that neither begin nor end with those values who fall within the range.

[0044] It should be noted that in aspects of the present application, the present application is described only once in one aspect of the aspects for the same component or term in the aspects and is not repeatedly described, and the person skilled in the art should not understand it as a limitation of the present application.

[0045] As used herein the terms "about" and "substantially" mean approximately or nearly, as in "about 90%," "substantially disabled," or "substantially similar." In one embodiment, the term "about" and "substantially" refers to a value that is within 10% of the stated value, preferably within 1% of the stated value, and more preferably within 0.1% of the stated value.

[0046] "Made from" is synonymous with "comprising." The terms "comprising," "including," "containing," "having" or any other similar forms are intended to be open-ended, and include one or more steps, integers, compositions and / or components that can be present, but not exclude the presence of other steps, integers, compositions, and / or components. The term "comprising" encompasses "including" and "including but not limited to."

[0047] The transitional phrase "consisting of" excludes any element, step, or ingredient not specified. If used in the claims, this phrase shall not be construed to mean that the noted elements or steps are essential to the practice of the claims. The phrase "consisting of" does not foreclose the addition of additional steps, ingredients, components, or steps to those listed in the claims. The phrase "consisting of" does not foreclose the use of optional steps, ingredients, components, or steps in the claims. The transitional phrase "consisting of" excludes any element, step, or ingredient not specified, but does not foreclose the use of optional ingredients or steps in the claims.

[0048] When equivalent, concentration, or other value or parameter is expressed in a range, a preferred range, or a series of upper preferred values and lower preferred values, it is to be understood that all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, even if the range is not explicitly disclosed, are to be specifically disclosed. For example, if a range "1-5" is disclosed, then the range "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. are to be specifically disclosed. When numerical ranges are disclosed, unless otherwise stated, the range is intended to include all integers and fractions within the range.

[0049] In these embodiments, the parts and percentages described are by mass, unless otherwise indicated.

[0050] "Mass parts" refers to a basic unit of measurement that represents the mass ratio relationship of multiple components, 1 part can represent any unit mass, such as 1 g, 2.689 g, etc. If we say that the mass parts of component A is a parts, and the mass parts of component B is b parts, it means that the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK, and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that unlike mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0051] "And / or" is used to indicate that one or both of the described situations can occur, for example, A and / or B includes (A and B) and (A or B).

[0052] In the present application, particle size D50 and average particle size have the same meaning, which refers to the particle size corresponding to the cumulative particle size distribution percentage of 50% of the positive electrode material precursor.

[0053] As described previously, the first aspect of the present application provides a sodium-ion battery positive electrode material, the sodium-ion battery positive electrode material comprising a substrate and a coating layer coated on at least part of the surface of the substrate;

[0054] The chemical formula of the substrate is Na x Ni a Fe b Mn c M d O2, wherein 0.85≤x≤1.1, 0

[0055] The coating layer comprises a metallo-metaphosphonate, and the metal element in the metallo-metaphosphonate is selected from at least one of Y, La, Al, Li, Na, Ba, and Ca.

[0056] In some embodiments, in the chemical formula of the substrate, 0.2≤a≤0.4, 0

[0057] In some embodiments, the M is selected from at least two of Ti, Mg, Cu, Ca, and Zn.

[0058] In some embodiments, the metal element in the metallo-metaphosphonate is selected from at least one of Y, Al, and Li.

[0059] In some embodiments, the mass of the metal element in the coating layer is 0.1wt%-1wt% based on the total mass of the substrate, which can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, and 1wt%.

[0060] In some embodiments, the mass of the metal element in the coating layer is 0.2wt%-0.5wt% based on the total mass of the substrate.

[0061] The mass of the metal element in the coating layer within this range is beneficial to balance the specific capacity and the cycle performance.

[0062] In some embodiments, the substrate comprises at least one phase structure of P2, O2, P3, or O3, and optionally, the substrate is in the O3 phase structure.

[0063] In some embodiments, when the substrate is in the O3 phase structure, the material has a high capacity, and the coating layer cooperates with the substrate to reduce side reactions while maintaining high capacity, thereby improving the rate charge-discharge performance and the cycle stability of the sodium-ion battery.

[0064] In some embodiments, the average thickness of the coating layer is 1-100nm, which can be 1nm, 5nm, 10nm, 20nm, 40nm, 60nm, 80nm, 100nm, or any value between 1nm and 100nm.

[0065] In some embodiments, the particle size D50 of the sodium-ion battery anode material is 4-8μm, which can be 4μm, 5μm, 6μm, 7μm, 8μm, or any value between 4μm and 8μm.

[0066] In some embodiments, the specific surface area (BET) of the sodium-ion battery cathode material is 0.3-0.8 m². 2 / g, for example, can be 0.3m 2 / g, 0.4m 2 / g, 0.5m 2 / g, 0.6m 2 / g, 0.7m 2 / g, 0.8m 2 / g or 0.3-0.8m 2 Any value between / g.

[0067] In some embodiments, the compaction density of the sodium-ion battery cathode material is 3.0-3.3 g / cm³. 3 For example, it can be 3.0 g / cm³. 3 3.1g / cm 3 3.2g / cm 3 3.3g / cm 3 Or 3.0-3.3 g / cm³ 3 Any value between.

[0068] As mentioned above, a second aspect of the present invention provides a method for preparing the sodium-ion battery cathode material described in the first aspect, the method comprising the following steps:

[0069] The matrix material and the metaphosphate metal salt are mixed to obtain a mixture;

[0070] The mixture is sintered in an oxygen-containing atmosphere to obtain the sodium-ion battery cathode material.

[0071] In some embodiments, the mixing conditions include a rotation speed of 1000-2000 rpm and a mixing time of 15-50 min.

[0072] In some embodiments, the matrix material is prepared by calcining a mixture I containing a sodium source and a sodium-ion battery cathode material precursor I containing Ni, Fe, Mn, and M1 elements in an air atmosphere. Optionally, the mixture I further contains an M2 source, wherein M1 and M2 are each independently selected from at least one of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W, and M1 and M2 are different.

[0073] In some embodiments, the base material is prepared by calcining treatment II of a mixture II containing a sodium source, a sodium-ion battery cathode material precursor II comprising Ni element, Fe element, Mn element, and M source, wherein M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W.

[0074] In some embodiments, the base material is prepared by calcining treatment III of a mixture III containing a sodium source, a nickel source, an iron source, a manganese source, and a M source, wherein M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W.

[0075] In some embodiments, the mass percentage of the metal element in the meta-phosphoric acid metal salt is 0.1wt%-1wt% based on the total mass of the base material, for example, the mass percentage of the metal element can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, or any value between 0.1wt% and 1wt%, optionally 0.2wt%-0.5wt%.

[0076] In some embodiments, the sintering treatment has a temperature of 400-700℃, for example, 400℃, 450℃, 500℃, 550℃, 600℃, or any value between 400-700℃; and a holding time of 5-8h, for example, 5h, 6h, 7h, 8h, or any value between 5-8h.

[0077] In some embodiments, the sintering treatment has a temperature of 400-700℃, for example, 400℃, 450℃, 500℃, 550℃, 600℃, or any value between 400-700℃; and a holding time of 5-8h, for example, 5h, 6h, 7h, 8h, or any value between 5-8h.

[0078] In some embodiments, the sodium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium oxalate, and sodium nitrate.

[0079] In some embodiments, the sodium-ion battery cathode material precursor I is selected from hydroxides containing Ni element, Fe element, Mn element, M1 element, and / or oxides containing Ni element, Fe element, Mn element, M1 element, and / or carbonates containing Ni element, Fe element, Mn element, M1 element.

[0080] In some embodiments, the mixture I further comprises a M2 source selected from at least one of oxides of M2, sulfates of M2, chlorides of M2, and nitrates of M2.

[0081] In some embodiments, the sodium-ion battery cathode material precursor II is selected from hydroxides containing Ni element, Fe element, Mn element and / or oxides containing Ni element, Fe element, Mn element and / or carbonates containing Ni element, Fe element, Mn element.

[0082] In some embodiments, the nickel source is selected from at least one of nickel oxide, nickel sulfate, nickel chloride, nickel hydroxide, nickel nitrate.

[0083] In some embodiments, the iron source is selected from at least one of diiron trioxide, ferroferric oxide, ferrous sulfate, iron sulfate, ferrous chloride, ferric chloride, ferrous nitrate, ferric nitrate.

[0084] In some embodiments, the manganese source is selected from at least one of manganese oxide, manganese sulfate, manganese chloride, manganese nitrate.

[0085] In some embodiments, the M source is selected from at least one of an oxide of M, a sulfate of M, a chloride of M, a nitrate of M.

[0086] In some embodiments, the conditions of the calcination treatment I, the calcination treatment II and the calcination treatment III each independently comprise: a temperature of 750-1050℃, for example, can be 750℃, 800℃, 900℃, 1000℃, 1050℃ or any value between 750-1050℃.

[0087] In some embodiments, the conditions of the calcination treatment I, the calcination treatment II and the calcination treatment III each independently comprise: a holding time of 10-14h, for example, can be 10h, 11h, 12h, 13h, 14h or any value between 10-14h.

[0088] In some embodiments, the conditions of the calcination treatment I, the calcination treatment II and the calcination treatment III each independently comprise: a heating rate of 1-5℃ / min, for example, can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min or any value between 1-5℃ / min.

[0089] In the preparation method of the sodium-ion battery cathode material described in the present application, post-treatment means known in the art such as cooling, crushing and sieving can also be included, so as to obtain a sodium-ion battery cathode material with better quality. The present application does not repeat here, and the person skilled in the art should not understand it as a limitation of the present application.

[0090] As previously described, the third aspect of the present application provides a sodium-ion battery, which comprises the sodium-ion battery cathode material as described in the aforementioned first aspect or the sodium-ion battery cathode material prepared by the preparation method as described in the aforementioned second aspect.

[0091] As previously described, the fourth aspect of the present application provides an electrical equipment, which comprises the sodium-ion battery as described in the aforementioned third aspect.

[0092] The present application will be described in detail below by way of examples. In the following examples, the raw materials are all commercially available products unless otherwise specified.

[0093] The metal metaphosphate salts used in the following examples are all high-purity metal metaphosphate salts with a purity of more than 99%.

[0094] Aluminum metaphosphate: Al(PO3)3;

[0095] Lithium metaphosphate: LiPO3;

[0096] Yttrium metaphosphate: Y(PO3)3;

[0097] Lanthanum metaphosphate: La(PO3)3.

[0098] The following preparation examples are used to illustrate the preparation process of the base material:

[0099] Preparation Example 1: Preparation of a base material with a chemical formula of Na 0.95 Ni 0.28 Fe 0.17 Mn 0.35 Ti 0.09 Mg 0.06 Cu 0.05 O2:

[0100] S1: Sodium carbonate, nickel oxide, iron oxide, manganese carbonate, titanium dioxide, magnesium oxide, and copper oxide are taken in a molar ratio of (0.95x1.03):0.28:0.17:0.35:0.09:0.06:0.05 (wherein "1.03" in "0.95x1.03" is a supplementary coefficient to prevent sodium volatilization at high temperatures), and a high-speed mixer is used to mix them thoroughly to obtain a mixed material III;

[0101] S2: The mixed material III is subjected to calcination treatment III under an air atmosphere (heated to 960℃ at a heating rate of 2℃ / min and kept for 12h), and after cooling to room temperature, it is crushed and sieved to obtain a base material Na 0.95 Ni 0.28 Fe 0.17 Mn 0.35Ti 0.09 Mg 0.06 Cu 0.05 O2.

[0102] Preparation Example 2: Preparation of a matrix material of the chemical formula Na 0.95 Ni 0.28 Fe 0.17 Mn 0.44 Mg 0.06 Cu 0.05 O2:

[0103] S1: Sodium carbonate, Ni 0.315 Fe 0.157 Mn 0.528 (OH)2, magnesium oxide, copper oxide were taken in a molar ratio of (0.95 x 1.03): 0.89: 0.06: 0.05, and were mixed thoroughly using a high-speed mixer to obtain a mixture II;

[0104] S2: The mixture II was subjected to calcination treatment II (raised to 960°C at a temperature raising rate of 2°C / min, and kept for 12h) under an air atmosphere to obtain a matrix material of the chemical formula Na 0.95 Ni 0.28 Fe 0.17 Mn 0.44 Mg 0.06 Cu 0.05 O2.

[0105] Preparation Example 3: Preparation of a matrix material of the chemical formula Na 0.95 Ni 0.28 Fe 0.17 Mn 0.35 Ti 0.09 Cu 0.11 O2:

[0106] S1: Sodium carbonate, Ni 0.308 Fe 0.187 Mn 0.385 Cu 0.121 (OH)2, and TiO2 were taken in a molar ratio of (0.95 x 1.03): 0.91: 0.09, and were mixed thoroughly using a high-speed mixer to obtain a mixture I;

[0107] S2: The mixture I was subjected to calcination treatment I (raised to 960°C at a temperature raising rate of 2°C / min, and kept for 12h) under an air atmosphere to obtain a matrix material of the chemical formula Na 0.95 Ni 0.28 Fe 0.17 Mn 0.35 Ti 0.09 Cu 0.11 O2.

[0108] Preparation Example 4: Preparation of a matrix material of the chemical formula Na 0.9 Ni 0.3 Mn 0.4 Ti 0.15 Mg 0.07 Cu 0.08 O2.

[0109] S1 : Sodium carbonate, nickel oxide, manganese carbonate, titanium dioxide, magnesium oxide, and copper oxide were taken according to the molar ratio of each metal element of (0.9 x 1.03): 0.3: 0.4: 0.15: 0.07: 0.08, and a high-speed mixer was used for sufficient mixing to obtain a mixture III;

[0110] S2: The mixture III was subjected to calcination treatment III under an air atmosphere (raised to 960°C at a temperature raising rate of 2°C / min, and kept for 12h), to obtain a matrix material Na 0.9 Ni 0.3 Mn 0.4 Ti 0.15 Mg 0.07 Cu 0.08 O2.

[0111] Preparation Example 5: Preparation of a matrix material of the chemical formula Na 0.94 Ni 0.32 Mn 0.43 Ti 0.1 Mg 0.07 Cu 0.08 O2.

[0112] S1 : Sodium carbonate, nickel oxide, manganese carbonate, titanium dioxide, magnesium oxide, and copper oxide were taken according to the molar ratio of each metal element of (0.94 x 1.03): 0.32: 0.43: 0.1: 0.07: 0.08, and a high-speed mixer was used for sufficient mixing to obtain a mixture III;

[0113] S2: The mixture III was subjected to calcination treatment III under an air atmosphere (raised to 960°C at a temperature raising rate of 2°C / min, and kept for 12h), to obtain a matrix material Na 0.94 Ni 0.32 Mn 0.43 Ti 0.1 Mg 0.07 Cu 0.08 O2.

[0114] Examples 1-10

[0115] Examples 1-10 Sodium ion battery cathode materials were prepared according to the following steps of the method with reference to the formulation in Table 1:

[0116] Mixing the base material and the metal metaphosphate salt to obtain a mixture;

[0117] The mixing condition: the rotating speed is 2000 rpm, and the time is 20 min;

[0118] Sintering the mixture in an oxygen-containing atmosphere, and then cooling, crushing and sieving to obtain the sodium ion battery cathode material;

[0119] The sintering condition: the temperature is increased to 500℃ at a rate of 2℃ / min, and the holding time is 6 h.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 1 is that the base material prepared in Preparation Example 1 is directly sintered, and then cooled, crushed and sieved to obtain the sodium ion battery cathode material;

[0122] For details, refer to Table 1, and the parts not listed are the same as Example 1.

[0123] Comparative Example 2

[0124] The difference between this comparative example and Example 1 is that Al2O3 is used to replace the metal metaphosphate salt in Example 1, and the amount of Al2O3 is controlled so that the amount of Al element in the Al2O3 is 0.2wt% based on the total mass of the base material, to obtain the sodium ion battery cathode material;

[0125] For details, refer to Table 1, and the parts not listed are the same as Example 1.

[0126] Comparative Example 3

[0127] The difference between this comparative example and Example 1 is that AlF3 is used to replace the metal metaphosphate salt in Example 1, and the amount of AlF3 is controlled so that the amount of Al element in the AlF3 is 0.2wt% based on the total mass of the base material, to obtain the sodium ion battery cathode material;

[0128] For details, refer to Table 1, and the parts not listed are the same as Example 1.

[0129] Comparative Example 4

[0130] The difference between this comparative example and Comparative Example 1 is that the base material used is the base material prepared in Preparation Example 4, which is sintered, and then cooled, crushed and sieved to obtain the sodium ion battery cathode material;

[0131] For details, refer to Table 1, and the parts not listed are the same as Comparative Example 1.

[0132] Comparative Example 5

[0133] The difference between the present comparative example and Comparative Example 1 is that the base material used is the base material prepared in Preparation Example 5, which is subjected to a sintering treatment, and then cooled, crushed and sieved to obtain the sodium ion battery positive electrode material.

[0134] For details, see Table 1, and the parts not listed are the same as Comparative Example 1.

[0135] Comparative Example 6

[0136] The present comparative example is carried out by a method similar to Example 1, except that the base material used is the base material prepared in Preparation Example 4.

[0137] For details, see Table 1, and the parts not listed are the same as Example 1.

[0138] Comparative Example 7

[0139] The present comparative example is carried out by a method similar to Comparative Example 2, except that the base material used is the base material prepared in Preparation Example 4.

[0140] For details, see Table 1, and the parts not listed are the same as Comparative Example 2.

[0141] Table 1: Types and amounts of raw materials in Examples and Comparative Examples

[0142]

[0143]

[0144] Test Example 1

[0145] 1. Physicochemical tests were performed on the sodium ion battery positive electrode materials prepared in the foregoing examples and comparative examples, and the test results are shown in Table 2.

[0146] Specifically:

[0147] (1) Particle size D50 was tested using a Malvern 3000 laser particle size analyzer, with reference to standard GB / T 19077-2016.

[0148] (2) The compaction density test conditions (reference standard GB / T 44330-2024) were tested using a Sansi UIM 7305 compaction density instrument, and the test method was as follows: 1 g of the material to be tested was weighed into a clean mold, the radius of the hole in the mold was 6.5 mm, then the mold was placed on the equipment pressure plate, and a test pressure of 3T was selected for testing.

[0149] (3) The specific surface area (BET) was determined according to GB / T 19587-2017 Gas Adsorption BET Method for Determining Solid Substances.

[0150] Table 2 Summary of parameters of the positive electrode materials prepared in the examples and comparative examples

[0151] D50 / pm BET / m 2 / g]]> Compacted density g / cm 3 ]]> pH Example 1 6.93 0.55 3.19 11.82 Example 5 7.12 0.58 3.21 11.62 Example 7 6.78 0.57 3.20 11.59 Comparative Example 1 6.72 0.58 3.18 11.91 Comparative Example 2 7.08 0.59 3.20 11.73

[0152] 2. The substrate material prepared in the aforementioned Preparation Example 1 and the sodium-ion battery positive electrode material prepared in the aforementioned Example 1 were subjected to X-ray diffraction (XRD) testing according to the method specified in GB / T 40407-2021, wherein the scanning range was 5°-80°, the scanning speed was 8° / min, the step angle was 0.02°, the soller slits were 5°, and the results are shown in FIG. 2. Figure 1

[0153] 3. The microstructure of the sodium-ion battery positive electrode material prepared in the aforementioned Example 1 was tested using a scanning electron microscope, and the results are shown in FIG. 3. Figure 2

[0154] Test Example 2

[0155] Preparation of a sodium-ion battery:

[0156] (1) The aforementioned sodium-ion battery positive electrode material, conductive agent (Super P), and binder (polyvinylidene fluoride PVDF) were weighed according to a mass ratio of 85:10:5 and placed in a weighing bottle, an appropriate amount of dispersion solvent (N-methyl pyrrolidone NMP) was added, and after stirring uniformly, it was coated on an aluminum foil, followed by drying, rolling, and slicing to prepare the desired positive electrode sheet;

[0157] (2) The battery shell, positive electrode sheet, negative electrode sheet (metallic sodium sheet), separator (glass fiber), spring, gasket, and electrolyte (1 mol / L NaClO4 solution) were assembled into a CR2032 button cell in a vacuum glove box.

[0158] The electrochemical performance of the prepared sodium-ion battery was tested using a blue electric test system CT3002A, and the details are as follows (1C = 150 mA / g):

[0159] ① Normal temperature performance test: the voltage range was set to 2-4.3 V, and the test method was as follows: 2 cycles of activation at 0.1C, 2 cycles of activation at 0.2C, and finally 100 cycles of activation at 1C, and the test temperature was 25±1℃; the test results are shown in Table 3:

[0160] ② High temperature performance test: the voltage range was set to 2-4.3 V, and the test method was as follows: 2 cycles of activation at 0.1C, 2 cycles of activation at 0.2C, and finally 100 cycles of activation at 1C, and the test temperature was 45±1℃;

[0161] ​​The first coulombic efficiency = the 1st cycle discharge capacity activated at 0.1C / the 1st cycle charge capacity activated at 0.1C * 100%;

[0162] The capacity retention rate after 100 cycles = the 100th cycle discharge capacity / the 1st cycle discharge capacity * 100%.

[0163] Table 3. Test results of the electrical properties of the positive electrode materials prepared in the examples and the comparative examples

[0164]

[0165] It can be seen from the above results that the sodium ion battery positive electrode material provided by the application can better alleviate the dissolution of iron ions and at the same time improve the diffusion rate of sodium ions; after being assembled into a sodium ion battery, it can have excellent first coulombic efficiency, first cycle capacity and cycle retention rate at room temperature and high temperature.

[0166] The above describes the preferred embodiments of the application, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and fall within the protection scope of the application.

Claims

1. A sodium-ion battery cathode material, characterized in that, The sodium-ion battery cathode material includes a matrix and a coating layer covering at least a portion of the surface of the matrix; The chemical formula of the matrix is ​​Na. x Ni a Fe b Mn c M d O2, where 0.85≤x≤1.1, 0<a<1, 0<b<1, 0<c<1, 0<d<0.5, a+b+c+d=1, and M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W; The coating layer comprises a metaphosphate metal salt, wherein the metal element in the metaphosphate metal salt is selected from at least one of Y, La, Al, Li, Na, Ba, and Ca.

2. The sodium-ion battery cathode material according to claim 1, characterized in that, In the chemical formula of the matrix, 0.2≤a≤0.4, 0<b≤0.3, 0.3≤c≤0.5, and 0.1≤d≤0.

3.

3. The sodium-ion battery cathode material according to claim 1, characterized in that, Based on the total mass of the substrate, the mass of the metal element in the coating layer is 0.1wt%-1wt%, and optionally, the mass of the metal element in the coating layer is 0.2wt%-0.5wt%.

4. The sodium-ion battery cathode material according to claim 1, characterized in that, The matrix comprises at least one phase structure selected from P2, O2, P3 or O3, and optionally, the matrix is ​​an O3 phase structure.

5. The sodium-ion battery cathode material according to any one of claims 1-4, characterized in that, The sodium-ion battery cathode material satisfies at least one of the following conditions: ①The particle size D50 of the sodium-ion battery cathode material is 4-8 μm; ② The specific surface area (BET) of the sodium-ion battery cathode material is 0.3-0.8 m². 2 / g; ③ The compaction density of the sodium-ion battery cathode material is 3.0-3.3 g / cm³. 3 ; ④ The M is selected from at least two of Ti, Mg, Cu, Ca, and Zn; ⑤ The metal element in the metaphosphate metal salt is selected from at least one of Y, Al, and Li.

6. A method for preparing the sodium-ion battery cathode material according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: The matrix material and the metaphosphate metal salt are mixed to obtain a mixture; The mixture is sintered in an oxygen-containing atmosphere to obtain the 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 matrix material is prepared by calcining a mixture I containing a sodium source and a sodium-ion battery cathode material precursor I containing Ni, Fe, Mn, and M1 elements in an air atmosphere. Optionally, the mixture I also contains an M2 source. M1 and M2 are each independently selected from at least one of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn, and W, and M1 and M2 are different. B. The matrix material is prepared by calcining a mixture of sodium source, sodium-ion battery cathode material precursor II containing Ni, Fe and Mn elements and M source II in an air atmosphere. M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn and W. C. The matrix material is prepared by calcining a mixture containing sodium source, nickel source, iron source, manganese source and M source III in an air atmosphere, wherein M is selected from at least two of Ti, Mg, Cu, Ca, Al, Zn, La, Cr, Y, Ce, Si, Sn and W. D. Based on the total mass of the matrix material, the mass percentage of the metal element in the metaphosphate metal salt is 0.1wt%-1wt%, and can be selected as 0.2wt%-0.5wt%. E. The conditions for the sintering treatment include: a temperature of 400-700℃ and a holding time of 5-8h.

8. The preparation method according to claim 7, characterized in that, The preparation method satisfies at least one of the following conditions: (1) The sodium source is selected from at least one of sodium carbonate, sodium hydroxide, sodium oxalate and sodium nitrate; (2) The sodium-ion battery cathode material precursor I is selected from hydroxides containing Ni, Fe, Mn and M1 elements and / or oxides containing Ni, Fe, Mn and M1 elements and / or carbonates containing Ni, Fe, Mn and M1 elements. (3) The sodium-ion battery cathode material precursor II is selected from hydroxides containing Ni, Fe and Mn elements and / or oxides containing Ni, Fe and Mn elements and / or carbonates containing Ni, Fe and Mn elements. (4) The nickel source is selected from at least one of nickel oxide, nickel sulfate, nickel chloride, nickel hydroxide, and nickel nitrate; and / or the iron source is selected from at least one of ferric oxide, ferric oxide, ferrous sulfate, ferric sulfate, ferrous chloride, ferric chloride, ferrous nitrate, and ferric nitrate; and / or the manganese source is selected from at least one of manganese oxide, manganese sulfate, manganese chloride, and manganese nitrate; and / or the M source is selected from at least one of oxide of M, sulfate of M, chloride of M, and nitrate of M; and / or the M2 source is selected from at least one of oxide of M2, sulfate of M2, chloride of M2, and nitrate of M2. (5) The conditions for calcination treatment I, calcination treatment II and calcination treatment III each independently include: a temperature of 750-1050℃; and / or a holding time of 10-14h; And / or the heating rate is 1-5℃ / min.

9. A sodium-ion battery, characterized in that, The sodium-ion battery includes the sodium-ion battery cathode material as described in any one of claims 1-5 or the 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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