Modified layered oxide positive electrode material and preparation method and application thereof

Abstract

The embodiment of the invention relates to a modified layered oxide positive electrode material and a preparation method and application thereof, and belongs to the technical field of sodium ion batteries. The modified layered oxide positive electrode material provided by the embodiment of the invention comprises an inner core and a coating layer coating at least part of the surface of the inner core, the coating layer comprises NaaCabAc (PO4) d, A is selected from at least one of Li, Mg, Al, K, Ti, V, Cr, Ni, Fe, Co, Mn, Cu, Zn, Zr, Nb, Mo, Sn, Ta, W, Sb or La, and 0 lt; a < = 4, 0lt; b < = 2, 0 < = c < = 2, 1 < = d < = 3, the valence of A is + m, and a + 2b + mc-3d = 0; the inner core comprises NaxMyMnzO2, M is selected from at least one of Li, Mg, Al, K, Ti, V, Cr, Ni, Fe, Co, Cu, Zn, Zr, Nb, Mo, Sn, Ta, W, Sb or La, and 0 lt; x is less than or equal to 1, 0lt; yt; Yt; 1, 0lt; and z < = 0.8. The preparation method provided by the embodiment of the invention is simple and easy to control, low in preparation cost and suitable for industrial production.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of sodium ion batteries, and in particular to a modified layered oxide positive electrode material and a preparation method and application thereof. Background Art

[0002] At present, lithium-ion batteries, as the main representative of electrochemical energy storage, can greatly improve the utilization efficiency of renewable energy. However, with the rapid development of electric vehicles around the world, the demand for power batteries is growing. In addition, the global lithium resource reserves are limited, expensive and unevenly distributed, making it difficult to meet the needs of power vehicles and large-scale energy storage at the same time. Sodium-ion batteries, with their advantages of abundant resources, wide distribution, low cost and high safety, can be used as a beneficial supplement to lithium-ion batteries and emerge in the fields of low-speed electric vehicles and large-scale energy storage.

[0003] Layered oxide cathode materials include oxides, polyanions, Prussian blue and organic materials. Among them, layered oxides have high theoretical specific capacity, moderate operating voltage, high compaction density, low toxicity and are easy to prepare on a large scale. They have attracted widespread attention from the scientific research and industrial communities and are considered to have the greatest potential for commercial applications. However, they still face a series of challenges. The first and most urgent issue is to reduce the residual alkali content on the surface of layered oxide cathode materials, because excessive residual alkali will make it difficult to process the material into pole pieces, and will also cause rapid capacity decay, which is a major problem hindering their commercial application. Summary of the invention

[0004] In view of this, the embodiments of the present application provide a modified layered oxide positive electrode material and a preparation method and application thereof, which directly reacts with the residual alkali (Na2CO3 and NaOH, etc.) on the surface of the layered oxide to generate a coating layer. On the one hand, the residual alkali on the surface of the layered oxide is reduced, and on the other hand, a dense coating layer is formed in situ, which can achieve the effect of stabilizing the structure and inhibit the occurrence of side reactions with the electrolyte, thereby significantly improving the processing performance and cycle stability of the layered oxide. At the same time, the preparation method of the present application is simple and easy to control, with low preparation cost, suitable for industrial production, and can effectively overcome the defects of the above-mentioned prior art.

[0005] In a first aspect, an embodiment of the present application provides a modified layered oxide positive electrode material, comprising a core and a coating layer coated on at least a portion of the surface of the core;

[0006] The coating layer includes Na a Ca b A c (PO4) d, wherein A is selected from at least one of Li, Mg, Al, K, Ti, V, Cr, Ni, Fe, Co, Mn, Cu, Zn, Zr, Nb, Mo, Sn, Ta, W, Sb or La, 0 < a ≤ 4, 0 < b ≤ 2, 0 ≤ c ≤ 2, 1 ≤ d ≤ 3, the valence of A is +m, and a + 2b + mc - 3d = 0;

[0007] The core includes Na x M y Mn z O2, wherein M is selected from at least one of Li, Mg, Al, K, Ti, V, Cr, Ni, Fe, Co, Cu, Zn, Zr, Nb, Mo, Sn, Ta, W, Sb or La, 0 < x ≤ 1, 0 < y < 1, 0 < z ≤ 0.8.

[0008] In some embodiments that may include the above embodiments, based on the total mass of the modified layered oxide cathode material, the mass percentage content W of the coating layer satisfies 0.2 ≤ W ≤ 5%.

[0009] In some embodiments that may include the above embodiments, the coating layer is selected from at least one of NaCaPO4, NaCaV(PO4)2, NaCaAl(PO4)2, Na2CaMg(PO4)2, Na2CaZn(PO4)2, Na3CaMn(PO4)3, NaCaFe(PO4)2, Na3CaTi(PO4)3 or Na3CaZr(PO4)3.

[0010] In some embodiments that may include the above embodiments, the core is selected from at least one of NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, NaCu 0.1 Ni 0.3 Fe 0.2 Ti 0.2 Mn 0.2 O2, NaFe 0.2 Co 0.2 Ti 0.2 Ni 0.2 Li 0.1 Mn 0.1 O2 or NaCo 1 / 4 Ni 1 / 4 Ti 1 / 4 Fe 1 / 8 Mn 1 / 8 O2.

[0011] The second aspect of the embodiment of the present application further provides a method for preparing the above-mentioned modified layered oxide positive electrode material, comprising the following steps:

[0012] Step S1, dissolving calcium salt, A salt and phosphoric acid in a solvent, then adding the core material, stirring evenly to obtain a precursor slurry;

[0013] Step S2, spray drying the precursor slurry to obtain a precursor powder;

[0014] Step S3: calcining the precursor powder to obtain a modified layered oxide positive electrode material.

[0015] The third aspect of the embodiment of the present application further provides a method for preparing the above-mentioned modified layered oxide positive electrode material, comprising the following steps:

[0016] Step S1, weighing the calcium salt, the A salt, the phosphorus source and the core material according to the stoichiometric ratio, mixing them evenly and then drying them to obtain a precursor powder;

[0017] Step S2: calcining the precursor powder to obtain a modified layered oxide positive electrode material.

[0018] In some embodiments that may include the above embodiments, the calcination temperature is 500-1000° C., and the calcination time is 2-12 hours.

[0019] In some embodiments that may include the above embodiments, the calcium salt is selected from at least one of nitrates, acetates, oxides, hydroxides, carbonates or phosphates containing calcium element;

[0020] The A salt is selected from at least one of nitrates, acetates, chlorides, oxides, hydroxides, carbonates or phosphates containing the A element.

[0021] The phosphorus source is selected from at least one of ammonium phosphate, phosphoric acid, diammonium hydrogen phosphate or ammonium dihydrogen phosphate.

[0022] A fourth aspect of the embodiments of the present application further provides a battery, comprising the above-mentioned modified layered oxide positive electrode material or the modified layered oxide positive electrode material prepared by the above-mentioned method.

[0023] A fifth aspect of the embodiments of the present application further provides an electric vehicle or energy storage device, comprising the above-mentioned battery.

[0024] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0025] The modified layered oxide positive electrode material of the embodiment of the present application directly reacts with the residual alkali (Na2CO3 and NaOH, etc.) on the surface of the layered oxide to generate a coating layer. On the one hand, it reduces the residual alkali on the surface of the layered oxide, and on the other hand, it forms a dense coating layer in situ, which can achieve the effect of stabilizing the structure and inhibit the occurrence of side reactions with the electrolyte, thereby significantly improving the processing performance and cycle stability of the layered oxide. At the same time, the preparation process of the present application is simple and easy to control, the preparation cost is low, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a graph showing the first charge and discharge test results of a battery formed by the modified layered oxide positive electrode material in Example 1 of the present invention in the voltage range of 2-4V;

[0028] Figure 2 This is a graph showing the cycle performance test results of a battery formed by the modified layered oxide positive electrode material in Example 1 of the present invention in the voltage range of 2-4V;

[0029] Figure 3 This is a graph showing the first charge and discharge test results of the battery formed by the modified layered oxide positive electrode material in Example 2, Example 3, Example 4 and Example 5 of the present invention in the voltage range of 2-4V;

[0030] Figure 4 The graph is a test result of the cycle performance of the battery formed by the modified layered oxide positive electrode material in Example 2, Example 3, Example 4 and Example 5 of the present invention in the voltage range of 2-4V;

[0031] Figure 5 This is a graph showing the first charge and discharge test results of the battery formed by the modified layered oxide positive electrode material in Example 6, Example 7, Example 8 and Example 9 of the present invention in the voltage range of 2-4V;

[0032] Figure 6 This is a graph showing the test results of the cycle performance of batteries formed by the modified layered oxide positive electrode materials in Examples 6, 7, 8 and 9 of the present invention in the voltage range of 2-4V;

[0033] Figure 7 This is a graph showing the first charge and discharge test results of a battery formed of a layered oxide positive electrode material in Comparative Example 1 in the voltage range of 2-4V;

[0034] Figure 8 This is a graph showing the cycle performance test results of a battery formed of a layered oxide positive electrode material in Comparative Example 1 in the voltage range of 2-4V;

[0035] Fig. 9 The first charge and discharge test result diagram of the battery formed by the modified layered oxide positive electrode material in Comparative Example 2 and Comparative Example 3 in the voltage range of 2-4V;

[0036] Fig.10 This is a graph showing the cycle performance test results of the battery formed by the modified layered oxide positive electrode material in Comparative Examples 2 and 3 in the voltage range of 2-4V. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] In the following examples and comparative examples, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0039] Example 1

[0040] The modified layered oxide positive electrode material is composed of a core and a coating layer coated on at least part of the surface of the core, and the core material is: NaFe 0.2 Co 0.2 Ti 0.2 Ni 0.2 Li 0.1 Mn 0.1 O2, coating layer: NaCaV(PO4)2.

[0041] Specifically, based on the total mass of the modified layered oxide positive electrode material, the mass percentage W of the coating layer is 1%.

[0042] The method for preparing the modified layered oxide positive electrode material comprises the following steps:

[0043] (1) Calcium acetate, vanadium chloride and phosphoric acid were dissolved in ethanol according to the stoichiometric ratio, and then the core material NaFe 0.2 Co 0.2 Ti 0.2 Ni 0.2 Li 0.1 Mn 0.1 O2, stir evenly to obtain precursor slurry;

[0044] (2) spray drying the precursor slurry to obtain a precursor powder;

[0045] (3) The precursor powder is calcined at 600° C. for 5 h to obtain a modified layered oxide positive electrode material.

[0046] Example 2

[0047] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is NaCaPO4, and the preparation method in this example is the same as that in Example 1.

[0048] Example 3

[0049] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is NaCaAl(PO4)2, and the preparation method in this example is the same as that in Example 1.

[0050] Example 4

[0051] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is Na2CaMg(PO4)2, and the preparation method in this example is the same as that in Example 1.

[0052] Example 5

[0053] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is Na2CaZn(PO4)2, and the preparation method in this example is the same as that in Example 1.

[0054] Example 6

[0055] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is Na3CaMn(PO4)3, and the preparation method in this example is the same as that in Example 1.

[0056] Example 7

[0057] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is NaCaFe(PO4)2, and the preparation method in this example is the same as that in Example 1.

[0058] Example 8

[0059] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is Na3CaTi(PO4)3, and the preparation method in this example is the same as that in Example 1.

[0060] Example 9

[0061] The modified layered oxide positive electrode material is different from that in Example 1 in that the coating layer in this example is Na3CaZr(PO4)3, and the preparation method in this example is the same as that in Example 1.

[0062] Example 10

[0063] The modified layered oxide positive electrode material is different from that in Example 1 in that the mass percentage content W of the coating layer in this example is 0.2%. The preparation method of this example is the same as that of Example 1.

[0064] Embodiment 11

[0065] The modified layered oxide positive electrode material is different from that in Example 1 in that the mass percentage content W of the coating layer in this example is 3%. The preparation method of this example is the same as that of Example 1.

[0066] Example 12

[0067] The modified layered oxide positive electrode material is different from that in Example 1 in that the mass percentage content W of the coating layer in this example is 5%. The preparation method of this example is the same as that of Example 1.

[0068] Embodiment 13

[0069] Modified layered oxide positive electrode material, different from Example 1, the core material of this embodiment is: NaNi 1 / 3Fe 1 / 3 Mn 1 / 3 O2, the preparation method of this embodiment is the same as that of embodiment 1.

[0070] Embodiment 14

[0071] Modified layered oxide positive electrode material, different from Example 1, the core material of this embodiment is: Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2, the preparation method of this embodiment is the same as that of embodiment 1.

[0072] Embodiment 15

[0073] Modified layered oxide positive electrode material, different from Example 1, the core material of this embodiment is: NaCu 0.1 Ni 0.3 Fe 0.2 Ti 0.2 Mn 0.2 O2, the preparation method of this embodiment is the same as that of embodiment 1.

[0074] Example 16

[0075] Modified layered oxide positive electrode material, different from Example 1, the core material of this embodiment is: NaCo 1 / 4Ni 1 / 4 Ti 1 / 4 Fe 1 / 8 Mn 1 / 8 O2, the preparation method of this embodiment is the same as that of embodiment 1.

[0076] Embodiment 17

[0077] The modified layered oxide positive electrode material is composed of a core and a coating layer coated on at least part of the surface of the core, and the core material is: NaFe 0.2 Co 0.2 Ti 0.2 Ni 0.2 Li 0.1 Mn 0.1 O2, coating layer: NaCaV(PO4)2.

[0078] Specifically, based on the total mass of the modified layered oxide positive electrode material, the mass percentage W of the coating layer is 1%.

[0079] The method for preparing the modified layered oxide positive electrode material comprises the following steps:

[0080] (1) weighing calcium carbonate, vanadium pentoxide, diammonium hydrogen phosphate and core material according to the stoichiometric ratio, mixing them evenly, drying them, and ball milling them to obtain a precursor powder;

[0081] (2) The precursor powder is calcined at 900° C. for 2 h to obtain a modified layered oxide positive electrode material.

[0082] Embodiment 18

[0083] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is NaCaPO4, and the preparation method of this embodiment is the same as that of Example 17.

[0084] Embodiment 19

[0085] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: NaCaAl(PO4)2, and the preparation method of this embodiment is the same as that of Example 17.

[0086] Embodiment 20

[0087] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: Na2CaMg(PO4)2, and the preparation method of this embodiment is the same as that of Example 17.

[0088] Embodiment 21

[0089] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: Na2CaZn(PO4)2, and the preparation method of this embodiment is the same as that of Example 17.

[0090] Embodiment 22

[0091] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: Na3CaMn(PO4)3, and the preparation method of this embodiment is the same as that of Example 17.

[0092] Embodiment 23

[0093] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: NaCaFe(PO4)2, and the preparation method of this embodiment is the same as that of Example 17.

[0094] Embodiment 24

[0095] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: Na3CaTi(PO4)3, and the preparation method of this embodiment is the same as that of Example 17.

[0096] Embodiment 25

[0097] The modified layered oxide positive electrode material is different from Example 17 in that the coating layer of this embodiment is: Na3CaZr(PO4)3, and the preparation method of this embodiment is the same as that of Example 17.

[0098] Comparative Example 1

[0099] The layered oxide positive electrode material provided in this comparative example is the core material NaFe in Example 1. 0.2 Co 0.2 Ti 0.2 Ni 0. 2Li 0.1 Mn 0.1 O2, however, does not include the coating.

[0100] Comparative Example 2

[0101] The modified layered oxide positive electrode material provided in this comparative example is different in that the coating layer in this comparative example is NaMgPO4, which is different from the coating layer in the embodiment of the present invention.

[0102] Comparative Example 3

[0103] The modified layered oxide positive electrode material provided in this comparative example is different in that the coating layer in this comparative example is Na3Al(PO4)2, which is different from the coating layer in the embodiment of the present invention.

[0104] Test example

[0105] 1. Preparation of sodium ion batteries

[0106] The modified layered oxide positive electrode material is used in a sodium ion secondary battery. Specifically, the modified layered oxide positive electrode material is used as a positive electrode material for a sodium ion secondary battery. The assembly of the sodium ion secondary battery includes the following steps:

[0107] (1) Mixing the modified layered oxide positive electrode material powder with the conductive agent SP and the binder PVDF in a mass ratio of 8:1:1, adding the solvent N-methyl methyl pyrrolidone (NMP), and stirring evenly in a room temperature dry environment to form a slurry;

[0108] (2) The slurry in step (1) was evenly coated on the current collector aluminum foil, dried in an oven at 80°C for 12 h, cut into pole pieces with a diameter of 13 mm, dried at 120°C for 4 h under vacuum conditions, and then transferred to an Ar atmosphere glove box for standby use;

[0109] (3) CR2032 button cells were assembled in an argon glove box, with metallic sodium as the negative electrode and NaPF6 / (EC:DMC:PC) solution as the electrolyte.

[0110] 2. Electrochemical performance test

[0111]

[0112]

[0113] Table 1

[0114] Use constant current charge and discharge mode to perform charge and discharge tests in the 2-4V voltage range. Figure 1 and 2 As shown, it can be seen that the battery formed by the modified layered oxide positive electrode material in Example 1 of the present invention has a discharge specific capacity of 116.76 mAh / g at a current density of 0.1C, a first coulombic efficiency of 96.79%, a discharge specific capacity of 102.73 mAh / g at a current density of 1C, a discharge specific capacity of 94.65 mAh / g after 200 cycles at a rate of 1C, and a capacity retention rate of 92.13%.

[0115] like Figure 3 and 4As shown, it can be seen that the batteries formed by the modified layered oxide positive electrode materials in Examples 2, 3, 4 and 5 of the present invention have discharge specific capacities of 118.73 mAh / g, 117.4 mAh / g, 120.23 mAh / g and 116.32 mAh / g, respectively, at a current density of 0.1 C, and the first coulombic efficiencies are 93.35%, 94.11%, 95.84% and 102.35%, respectively; the discharge specific capacities at a current density of 1 C are 103.67 mAh / g, 106.4 mAh / g, 101 mAh / g and 104.37 mAh / g, respectively; the discharge specific capacities after 200 cycles at a rate of 1 C are 91.17 mAh / g, 97.35 mAh / g, 88.3 mAh / g and 92.25 mAh / g, respectively; and the capacity retention rates are 87.94%, 91.49%, 87.42% and 88.39%, respectively.

[0116] like Figure 5 and 6 As shown, it can be seen that the batteries formed by the modified layered oxide positive electrode materials in Examples 6, 7, 8 and 9 of the present invention have discharge specific capacities of 116.36 mAh / g, 115.66 mAh / g, 119.81 mAh / g and 118.78 mAh / g, respectively, at a current density of 0.1 C, and the first coulombic efficiencies are 94.27%, 93.85%, 95.35% and 104.14%, respectively; the discharge specific capacities at a current density of 1 C are 104.61 mAh / g, 104.46 mAh / g, 102.28 mAh / g and 101.86 mAh / g, respectively; the discharge specific capacities after 200 cycles at a rate of 1 C are 94.65 mAh / g, 93.01 mAh / g, 89.25 mAh / g and 87.36 mAh / g, respectively; and the capacity retention rates are 90.48%, 89.04%, 87.26% and 85.76%, respectively.

[0117] like Figure 7 and 8 As shown, it can be seen that the battery formed by the layered oxide positive electrode material in Comparative Example 1 has a discharge specific capacity of 114.65 mAh / g at a current density of 0.1C, a first coulombic efficiency of 84.25%, a discharge specific capacity of 102.54 mAh / g at a current density of 1C, a discharge specific capacity of 79.17 mAh / g after 200 cycles at a rate of 1C, and a capacity retention rate of 77.21%.

[0118] like Fig. 9 and 10As shown, it can be seen that the batteries formed by the modified layered oxide positive electrode materials in Comparative Examples 2 and 3 have a discharge specific capacity of 115.43 mAh / g and 115.82 mAh / g at a current density of 0.1 C, and the first coulombic efficiency is 86.56% and 87.74% respectively. The discharge specific capacity at a current density of 1 C is 105.56 mAh / g and 104.94 mAh / g respectively. After 200 cycles at a rate of 1 C, the discharge specific capacity is 87.11 mAh / g and 86.43 mAh / g respectively, and the capacity retention rate is 82.52% and 82.36% respectively.

[0119] Compared with the test results of Comparative Example 1, Comparative Example 2 and Comparative Example 3, the first coulombic efficiency and cycle performance of the modified layered oxide positive electrode materials in Example 1, Example 2, Example 3, Example 4, Example 5, Example 6, Example 7, Example 8, and Example 9 are significantly improved, which indicates that the first coulombic efficiency and cycle performance of the modified layered oxide positive electrode material in the present invention are better.

[0120] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A modified layered oxide positive electrode material, characterized in that: comprising a core and a coating layer coated on at least a portion of the surface of the core; The coating layer includes Na a Ca b A c (PO4) d , wherein A is selected from at least one of Li, Mg, Al, K, Ti, V, Cr, Ni, Fe, Co, Mn, Cu, Zn, Zr, Nb, Mo, Sn, Ta, W, Sb or La, 0 < a ≤ 4, 0 < b ≤ 2, 0 ≤ c ≤ 2, 1 ≤ d ≤ 3, the valence of A is +m, and a + 2b + mc - 3d = 0; The core includes Na x M y Mn z O2, wherein M is selected from at least one of Li, Mg, Al, K, Ti, V, Cr, Ni, Fe, Co, Cu, Zn, Zr, Nb, Mo, Sn, Ta, W, Sb or La, 0 <x≤1,0<y<1,0<z≤0.8。 2. The modified layered oxide positive electrode material according to claim 1, characterized in that: Based on the total mass of the modified layered oxide positive electrode material, the mass percentage W of the coating layer satisfies 0.2≤W≤5%.

3. The modified layered oxide positive electrode material according to claim 1, characterized in that: The coating layer is selected from at least one of NaCaPO4, NaCaV(PO4)2, NaCaAl(PO4)2, Na2CaMg(PO4)2, Na2CaZn(PO4)2, Na3CaMn(PO4)3, NaCaFe(PO4)2, Na3CaTi(PO4)3 or Na3CaZr(PO4)3.

4. The modified layered oxide positive electrode material according to claim 1, characterized in that: The core is selected from NaNi 1 / 3Fe 1 / 3 Mn 1 / 3 O2、Na 0.9 Cu 0.22 Fe 0.30 Mn 0.48 O2、NaCu 0.1 Ni 0.3 Fe 0.2 Ti 0.2 Mn 0.2 O2、NaFe 0.2 Co 0.2 Ti 0.2 Ni 0.2 Li 0.1 Mn 0.1 O2 or NaCo 1 / 4 Ni 1 / 4 Ti 1 / 4 Fe 1 / 8 Mn 1 / 8 At least one of O2.

5. A method for preparing the modified layered oxide positive electrode material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1, dissolving calcium salt, A salt and phosphoric acid in a solvent, then adding the core material, stirring evenly to obtain a precursor slurry; Step S2, spray drying the precursor slurry to obtain a precursor powder; Step S3: calcining the precursor powder to obtain a modified layered oxide positive electrode material.

6. A method for preparing the modified layered oxide positive electrode material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step S1, weighing the calcium salt, the A salt, the phosphorus source and the core material according to the stoichiometric ratio, mixing them evenly and then drying them to obtain a precursor powder; Step S2: calcining the precursor powder to obtain a modified layered oxide positive electrode material.

7. The preparation method according to claim 5 or 6, characterized in that: The calcination temperature is 500-1000° C., and the calcination time is 2-12 hours.

8. The preparation method according to claim 5 or 6, characterized in that: The calcium salt is selected from at least one of nitrates, acetates, oxides, hydroxides, carbonates or phosphates containing calcium; The A salt is selected from at least one of nitrates, acetates, chlorides, oxides, hydroxides, carbonates or phosphates containing the A element; The phosphorus source is selected from at least one of ammonium phosphate, phosphoric acid, diammonium hydrogen phosphate or ammonium dihydrogen phosphate.

9. A battery, characterized in that: The invention comprises the modified layered oxide positive electrode material as described in any one of claims 1 to 4 or the modified layered oxide positive electrode material prepared by the method as described in any one of claims 5 to 8.

10. An electric vehicle or energy storage device, characterized in that: A battery comprising the battery of claim 9.

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