Sodium-ion battery positive electrode modified material and preparation method thereof

Abstract

The invention provides a sodium ion battery positive electrode modified material and a preparation method thereof, and relates to the technical field of sodium ion battery materials. The preparation method of the sodium ion battery positive electrode modified material comprises the following steps: providing a nickel source, a manganese source and an iron source, preparing a transition metal oxide precursor, and preparing a single crystal NaNixFeyMnzO2 material from the transition metal oxide precursor and a sodium salt through a sintering process, 0.2 < = x < = 0.4, 0.1 < = y < = 0.4, 0.2 < = z < = 0.4, the single crystal NaNi < x > Fe < y > Mn < z > O < 2 > material is subjected to ion doping and co-coating treatment to obtain the sodium ion battery positive electrode modified material. The prepared battery positive electrode modified material can improve the cycling stability of the battery.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery materials technology, specifically to a sodium-ion battery cathode modification material and its preparation method. Background Technology

[0002] Lithium-ion batteries, as energy storage devices, have attracted much attention due to their high energy density, long cycle life, and eco-friendliness. However, the limited availability of lithium resources leads to increased costs, restricting the large-scale application of lithium-ion batteries. Sodium, due to its abundant reserves and similar physicochemical properties to lithium, is one of the ideal alternatives to lithium.

[0003] Sodium-ion battery cathode materials include layered oxides, polyanionic compounds, and Prussian blue analogues. Among these, layered oxides have a simple structure, low cost, and are easy to process and mass-produce. They also offer unique advantages in industrialization and supply chain compatibility and rapid switching with ternary cathodes in lithium-ion batteries. However, layered oxide materials inevitably undergo phase transitions during charge and discharge. Irreversible phase transitions lead to changes in material structure, resulting in poor electrochemical performance and cycle stability. Furthermore, the presence of Na+ in O3-type materials further complicates matters. + The slow diffusion rate results in low high-rate discharge capacity, which limits its practical development. Therefore, researching and developing layered oxides with high capacity and high stability is a crucial breakthrough for the industrial application of sodium-ion batteries. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a modified sodium-ion battery cathode material and its preparation method, solving the problems of phase transition during charge and discharge of layered oxide cathode materials and Na+. + Technical problem of slow diffusion rate.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] On one hand, the present invention provides a method for preparing a sodium-ion battery cathode modification material, comprising the following steps:

[0009] Nickel, manganese, and iron sources are provided to prepare transition metal oxide precursors. These precursors are then sintered with sodium salt to prepare single-crystal NaNi. x Fe y Mn z O2 material, 0.2≤x≤0.4, 0.1≤y≤0.4, 0.2≤z≤0.4, the single crystal NaNi x Fey Mn z O2 materials were used to obtain modified cathode materials for sodium-ion batteries through ion doping and co-coating.

[0010] The above preparation method first prepares single-crystal NaNi x Fe y Mn z O2 materials, with single-crystal NaNi x Fe y Mn z Using O2 as a matrix, sodium-ion battery cathode modified materials were obtained through ion doping and co-coating treatments. Single-crystal particles achieved better structural stability. The difference in ion radius between the doped and parent ions led to localized lattice distortion, optimizing the lattice structure and increasing the system energy, thereby suppressing phase transitions. Co-coating promoted the formation of Na+ ions. + The transmission of sodium ions reduces the internal resistance of the battery and increases the concentration of sodium ions in the battery, thereby enabling the prepared positive electrode material to improve the cycle stability of the battery.

[0011] Preferably, the ions used in the ion doping treatment include Zr. 4+ Ti 4+ Al 3+ Cu 2+ Zn 2+ Mg 2+ The co-coating materials include MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, UiO-66, and Na. 1+x Zr2Si 3-x O 12 (0≤x≤3), NaZr2(PO4)3, NaTi2(PO4)3 or NaGe2(PO4)3.

[0012] Preferably, the Na 1+x Zr2Si 3-x O 12 (0≤x≤3) is Na3Zr2Si2PO 12 .

[0013] Selecting Zr doped with heteroions 4+ Ti 4+ Al 3+ Cu 2+ Zn 2+ Mg 2+ Simultaneously, co-coating materials were selected for co-coating, because the heteroions and O 2−The bonding force between them is stronger. When TM-O is doped into the crystal lattice, the average bond length becomes shorter, and correspondingly, the Na-O bond lengthens. This optimizes the crystal structure, increases the sodium interlayer spacing, decreases the transition metal oxide interlayer spacing, and reduces the Na... + The diffusion resistance of Na promotes the diffusion of Na + The migration of Na+ improves the ionic conductivity of the material, increases the structural stability of the transition metal layer, and suppresses phase transitions, especially preventing irreversible phase transitions. MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, and UiO-66 possess high specific surface areas and porous structures, providing numerous reaction sites, increasing the specific capacity of the cathode material, and simultaneously promoting Na+ migration. + The transmission of [materials / materials]. MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, and UiO-66 can maintain their structure under extreme conditions such as high temperature, exhibiting extremely high stability, protecting the positive electrode material from electrolyte corrosion, and thus improving the battery's cycle performance. Na 1+x Zr2Si 3-x O 12 (0≤x≤3), NaZr2(PO4)3, NaTi2(PO4)3, or NaGe2(PO4)3 have abundant three-dimensional channels, Na + It can easily pass through the coating layer into the electrolyte. Na + The increased migration rate of Na leads to improved battery charge / discharge efficiency and power density. 1+x Zr2Si 3-x O 12 (0≤x≤3), NaZr2(PO4)3, NaTi2(PO4)3, or NaGe2(PO4)3 act as sodium supplements, increasing the sodium ion concentration in the battery and thus improving its energy density. Therefore, single-crystal O3 phase NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 Using O2 material as the matrix, the prepared cathode modified material exhibits excellent capacity utilization, rate performance, and cycle stability under the synergistic effect of doping heteroions and coating materials.

[0014] Preferably, the Zr 4+ Ti 4+ Al 3+ Cu 2+ Zn 2+ Mg 2+ The doping amount is NaNi x Fe y Mn z Na in O2 + 1-3% of the amount of substance.

[0015] Preferably, the coating amount of the co-coating material is single-crystal NaNi. x Fe y Mn z 0.05-0.2 wt% of O2 material.

[0016] Preferably, the single-crystal NaNi x Fe y Mn z The ion doping and co-coating treatment of O2 materials includes:

[0017] Single crystal NaNi x Fe y Mn z O2 material, heteroion source, and co-coated material are sintered in an O2 atmosphere at 300-500℃ with a heating rate of 1-5℃ / min for 6-12 hours and then ground.

[0018] The heteroion source is a zirconium source;

[0019] The zirconium source is Zr(NO3)4·5H2O, ZrO2, or ZrF4;

[0020] The above refers to single-crystal NaNi x Fe y Mn z O2 materials, along with a heteroion source and co-coating materials, are sintered in an O2 atmosphere to prepare single-crystal O3 phase NaNi. x Fe y Mn z Using O2 material as the matrix, a cathode modification material is formed by doping with hetero-ions and co-coating with a co-coating material, thereby leveraging the synergistic effect of the doping hetero-ions and the co-coating material in improving the capacity, rate performance, and cycle stability of the cathode modification material.

[0021] Preferably, the single-crystal NaNi x Fe y Mn z The mass ratio of O2 material, heteroion source, and co-coating material is 100:7-10:0.2-1.

[0022] Preferably, the single-crystal NaNi x Fe y Mn z The preparation process of O2 material includes: (1) adding the nickel source, iron source and manganese source to deionized water to form an aqueous solution, then adding chelating agent and dispersant and stirring to form a transparent sol, heating at high temperature to obtain polyethylene glycol ester gel, and aging to obtain a transition metal oxide precursor; (2) mixing the transition metal oxide precursor with sodium salt, pre-sintering under O2 atmosphere, and then sintering to obtain single crystal NaNi.x Fe y Mn z O2 materials;

[0023] The nickel source is selected from one or more of nickel acetate, nickel sulfate, nickel chloride, and nickel nitrate;

[0024] The manganese source is selected from one or more of manganese acetate, manganese sulfate, manganese chloride, and manganese nitrate;

[0025] The iron source is selected from one or more of ferrous sulfate, ferrous chloride, and ferric nitrate;

[0026] The sodium salt is selected from one or more of sodium carbonate, sodium bicarbonate, and sodium hydroxide.

[0027] In a second aspect, the present invention provides a sodium-ion battery cathode modification material, wherein the sodium-ion battery cathode modification material is prepared by the preparation method described in any one of claims 1-8.

[0028] Preferably, the sodium-ion battery cathode modification material comprises single-crystal O3 phase NaNi. x Fe y Mn z O2 matrix and a co-coating layer, wherein the co-coating layer coats the matrix, and the NaNi... x Fe y Mn z O2 matrix doped with Zr 4+ Ti 4+ Al 3+ Cu 2+ Zn 2+ Mg 2+ .

[0029] The aforementioned sodium-ion battery cathode modification materials include single-crystal O3 phase NaNi. x Fe y Mn z The O2 matrix and co-coating layer exhibit excellent capacity utilization, rate performance, and cycle stability.

[0030] The present invention has the following beneficial effects:

[0031] (1) O3-phase sodium ion layered oxides were synthesized using the Pechini sol-gel method without the prior addition of a sodium source. Single crystals could be synthesized simply by changing the precursor, without the need for excessively high calcination temperatures or subsequent washing treatments. The resulting single crystal particles exhibited better structural stability compared to standard polycrystalline materials, effectively suppressing the formation of intergranular cracks and particle fragmentation during cycling, thus significantly improving the cycle performance of the battery.

[0032] (2) Selective doping with Zr heteroions 4+ Ti 4+ Al 3+ Cu 2+ Zn 2+ Mg 2+ Simultaneously, co-coating materials were selected for co-coating. The heteroions optimized the crystal structure, increased the sodium interlayer spacing, decreased the transition metal oxide interlayer spacing, and reduced the Na+ content. + The diffusion resistance of Na promotes the diffusion of Na + The migration of Na+ improves the ionic conductivity of the material, increases the structural stability of the transition metal layer, and suppresses phase transitions, especially preventing irreversible phase transitions. MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, and UiO-66 possess high specific surface areas and porous structures, providing numerous reaction sites, increasing the specific capacity of the cathode material, and simultaneously promoting Na+ migration. + The transmission of [materials / materials]. MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, and UiO-66 can maintain their structure under extreme conditions such as high temperature, exhibiting extremely high stability, protecting the positive electrode material from electrolyte corrosion, and thus improving the battery's cycle performance. Na 1+x Zr2Si 3-x O 12 (0≤x≤3), NaZr2(PO4)3, NaTi2(PO4)3, or NaGe2(PO4)3 have abundant three-dimensional channels, Na + It can easily pass through the coating layer into the electrolyte. Na + The increased migration rate of Na leads to improved battery charge / discharge efficiency and power density. 1+x Zr2Si 3-x O 12 (0≤x≤3), NaZr2(PO4)3, NaTi2(PO4)3, or NaGe2(PO4)3 act as sodium supplements, increasing the sodium ion concentration in the battery and thus improving its energy density. Therefore, single-crystal O3 phase NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 Using O2 material as the matrix, and doped with Zr ions... 4+ Ti 4+ Al 3+ Cu 2+ Zn 2+ Mg 2+ and MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, UiO-66, Na 1+x Zr2Si3-x O 12 The prepared cathode modified material exhibits excellent capacity utilization, rate performance, and cycle stability under the synergistic effect of co-coating with NaZr2(PO4)3, NaTi2(PO4)3, or NaGe2(PO4)3 (0≤x≤3). Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] To better understand the above technical solution, the following will provide a detailed explanation of the above technical solution in conjunction with specific implementation methods.

[0035] I. Preparation Method

[0036] Example 1

[0037] This embodiment provides a method for preparing a modified cathode material for sodium-ion batteries, comprising the following steps:

[0038] (1) Nickel acetate tetrahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate were added to 50 ml of deionized water in a molar ratio of 1:1:1 to form an aqueous solution. 5 g of citric acid was added as a chelating agent, and 2.5 g of ethylene glycol was added as a dispersant, and the mixture was stirred until homogeneous to form a transparent sol. Excess water was evaporated by heating at 120 °C. Following the hydrolysis and condensation of the alkoxides, a polyethylene glycol ester gel was obtained and aged for 24 h. Drying and thermal decomposition at 250 °C for 4 h yielded a loose and porous transition metal oxide precursor.

[0039] (2) The precursor and Na2CO3 were mixed at a stoichiometric ratio of precursor:Na = 1:1.03. The mixed powder was heated to 500℃ at a heating rate of 3℃ / min under O2 atmosphere and pre-sintered for 5 h. Then, it was sintered at 900℃ for 12 h at the same heating rate to obtain single crystal NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material.

[0040] (3) Dissolve 0.322 g of zirconium oxychloride octahydrate and 0.210 g of trimesic acid in a 1:1 mixture of DMF and formic acid, and then place the mixture in a reactor at 135 °C for hydrothermal treatment for 48 h. After the temperature drops to room temperature, filter the liquid in the reactor, collect the white precipitate, and wash it with DMF and deionized water in sequence to remove unreacted substances. The resulting solid is dried under vacuum at 65 °C for 12 h to obtain MOF-808.

[0041] (4) Take 100 g NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 and 3.85 g Zr(NO3)4·5H2O, 0.05 g MOF-808, 0.05g Na3Zr2Si2PO 12 The sample was heated to 500℃ at a heating rate of 3℃ / min under an O2 atmosphere and sintered for 12 h. The calcined sample was then thoroughly ground to obtain Zr. 4+ Doping, MOF-808, Na3Zr2Si2PO 12 Coated and modified monocrystalline sodium-ion battery cathode material.

[0042] Example 2

[0043] This embodiment provides a method for preparing a modified cathode material for sodium-ion batteries, comprising the following steps:

[0044] (1) Nickel acetate tetrahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate were added to 50 ml of deionized water in a molar ratio of 1:1:1 to form an aqueous solution. 5 g of citric acid was added as a chelating agent, and 2.5 g of ethylene glycol was added as a dispersant, and the mixture was stirred until homogeneous to form a transparent sol. Excess water was evaporated by heating at 120 °C. Following the hydrolysis and condensation of the alkoxides, a polyethylene glycol ester gel was obtained and aged for 24 h. Drying and thermal decomposition at 250 °C for 4 h yielded a loose and porous transition metal oxide precursor.

[0045] (2) The precursor and Na2CO3 were mixed at a stoichiometric ratio of precursor:Na = 1:1.03. The mixed powder was heated to 500℃ at a heating rate of 3℃ / min under O2 atmosphere and pre-sintered for 5 h. Then, it was sintered at 900℃ for 12 h at the same heating rate to obtain single crystal NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material.

[0046] (3) Dissolve 0.322 g of zirconium oxychloride octahydrate and 0.210 g of trimesic acid in a 1:1 mixture of DMF and formic acid, and then place the mixture in a reactor at 135 °C for hydrothermal treatment for 48 h. After the temperature drops to room temperature, filter the liquid in the reactor, collect the white precipitate, and wash it with DMF and deionized water in sequence to remove unreacted substances. The resulting solid is dried under vacuum at 65 °C for 12 h to obtain MOF-808.

[0047] (4) Take 100 g NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 and 7.7 g Zr(NO3)4·5H2O, 0.05 g MOF-808, 0.05g Na3Zr2Si2PO 12 The sample was heated to 500℃ at a heating rate of 3℃ / min under an O2 atmosphere and sintered for 12 h. The calcined sample was then thoroughly ground to obtain Zr. 4+ Doping, MOF-808, Na3Zr2Si2PO 12 Coated and modified monocrystalline sodium-ion battery cathode material.

[0048] Example 3

[0049] This embodiment provides a method for preparing a modified cathode material for sodium-ion batteries, comprising the following steps:

[0050] (1) Nickel acetate tetrahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate were added to 50 ml of deionized water in a molar ratio of 1:1:1 to form an aqueous solution. 5 g of citric acid was added as a chelating agent, and 2.5 g of ethylene glycol was added as a dispersant, and the mixture was stirred until homogeneous to form a transparent sol. Excess water was evaporated by heating at 120 °C. Following the hydrolysis and condensation of the alkoxides, a polyethylene glycol ester gel was obtained and aged for 24 h. Drying and thermal decomposition at 250 °C for 4 h yielded a loose and porous transition metal oxide precursor.

[0051] (2) The precursor and Na2CO3 were mixed at a stoichiometric ratio of precursor:Na = 1:1.03. The mixed powder was heated to 500℃ at a heating rate of 3℃ / min under O2 atmosphere and pre-sintered for 5 h. Then, it was sintered at 900℃ for 12 h at the same heating rate to obtain single crystal NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material.

[0052] (3) Dissolve 0.322 g of zirconium oxychloride octahydrate and 0.210 g of trimesic acid in a 1:1 mixture of DMF and formic acid, and then place the mixture in a reactor at 135 °C for hydrothermal treatment for 48 h. After the temperature drops to room temperature, filter the liquid in the reactor, collect the white precipitate, and wash it with DMF and deionized water in sequence to remove unreacted substances. The resulting solid is dried under vacuum at 65 °C for 12 h to obtain MOF-808.

[0053] (4) Take 100 g NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 and 7.7 g Zr(NO3)4·5H2O, 0.1 g MOF-808, 0.05 gNa3Zr2Si2PO 12 The sample was heated to 500℃ at a heating rate of 3℃ / min under an O2 atmosphere and sintered for 12 h. The calcined sample was then thoroughly ground to obtain Zr. 4+ Doping, MOF-808, Na3Zr2Si2PO 12 Coated and modified monocrystalline sodium-ion battery cathode material.

[0054] Example 4

[0055] This embodiment provides a method for preparing a modified positive electrode material for batteries, comprising the following steps:

[0056] (1) Nickel acetate tetrahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate were added to 50 ml of deionized water in a molar ratio of 1:1:1 to form an aqueous solution. 5 g of citric acid was added as a chelating agent, and 2.5 g of ethylene glycol was added as a dispersant, and the mixture was stirred until homogeneous to form a transparent sol. Excess water was evaporated by heating at 120 °C. Following the hydrolysis and condensation of the alkoxides, a polyethylene glycol ester gel was obtained and aged for 24 h. Drying and thermal decomposition at 250 °C for 4 h yielded a loose and porous transition metal oxide precursor.

[0057] (2) The precursor and Na2CO3 were mixed at a stoichiometric ratio of precursor:Na = 1:1.03. The mixed powder was heated to 500℃ at a heating rate of 3℃ / min under O2 atmosphere and pre-sintered for 5 h. Then, it was sintered at 900℃ for 12 h at the same heating rate to obtain single crystal NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material.

[0058] (3) Dissolve 0.322 g of zirconium oxychloride octahydrate and 0.210 g of trimesic acid in a 1:1 mixture of DMF and formic acid, and then place the mixture in a reactor at 135 °C for hydrothermal treatment for 48 h. After the temperature drops to room temperature, filter the liquid in the reactor, collect the white precipitate, and wash it with DMF and deionized water in sequence to remove unreacted substances. The resulting solid is dried under vacuum at 65 °C for 12 h to obtain MOF-808.

[0059] (4) Take 100 g NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 and 7.7 g Zr(NO3)4·5H2O, 0.1 g MOF-808, 0.1 gNa3Zr2Si2PO 12 The sample was heated to 500℃ at a heating rate of 3℃ / min under an O2 atmosphere and sintered for 12 h. The calcined sample was then thoroughly ground to obtain Zr. 4+ Doping, MOF-808, Na3Zr2Si2PO 12 Coated and modified monocrystalline sodium-ion battery cathode material.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 4 is that steps (1) and (2) are different, specifically:

[0062] (1) An aqueous solution was formed by adding nickel acetate tetrahydrate, manganese acetate tetrahydrate, and ferric nitrate nonahydrate in a molar ratio of 1:1 to sodium acetate trihydrate in 50 ml of deionized water. Then, 10 g of citric acid was added as a chelating agent and 5 g of ethylene glycol as a dispersant and stirred to form a transparent sol. After drying, the precursor containing sodium source was obtained by thermal decomposition.

[0063] (2) The ground precursor powder was placed in a tube furnace and heated to 500°C at a heating rate of 3°C / min under an O2 atmosphere. It was pre-sintered for 5 h and then sintered at 900°C for 12 h at the same heating rate to obtain polycrystalline NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3O2 material.

[0064] Using polycrystalline NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material replacement in step (4) of Example 4: Single-crystal NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material, otherwise the same as in Example 4.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 2 and Example 4 is that step (4) does not include Zr(NO3)4·5H2O, and Zr is not processed. 4+ The doping is the same as in Example 4.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 3 and Example 4 is that step (4) does not include MOF-808 and MOF-808 is not coated. Otherwise, it is the same as Example 4.

[0069] Comparative Example 4

[0070] The difference between Comparative Example 4 and Example 4 is that step (4) does not include Na3Zr2Si2PO 12 Na3Zr2Si2PO was not performed. 12 The coating is the same as in Example 4.

[0071] II. Testing Methods

[0072] The positive electrode materials prepared in Examples 1-4 and Comparative Examples 1-4 were assembled according to the assembly method of button cells, and then the battery performance was tested.

[0073] The assembly method for button batteries is as follows: Positive electrode material, conductive agent SP, and binder PVDF are mixed in a mass ratio of 80:10:10 to form a slurry. N-methylpyrrolidone (NMP) is used to adjust the solid content of the slurry. The adjusted slurry is then coated onto aluminum foil (active material loading is 2-3 g / cm³). 2 The positive electrode was obtained by vacuum drying at 110℃ for 12 hours, followed by rolling and stamping. A sodium sheet was used as the negative electrode, and the electrolyte was 1 mol / L NaPF6 with a volume ratio of EC, PC, and FEC of 47.5:47.5:5. The cells were assembled into button cells in an argon-filled glove box.

[0074] Its electrochemical performance was tested using the Blue Electricity testing system.

[0075] III. Test Results

[0076] The electrochemical performance test results of the batteries corresponding to the cathode materials prepared in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1.

[0077] Table 1. Results of the button circuit test

[0078] <![CDATA[0.1C discharge capacity (mAh·g -1 )]]> <![CDATA[10C discharge capacity (mAh·g -1 )]]> Capacity retention rate (%) after 300 cycles at 1C Example 1 146.9 98.4 88.2% Example 2 147.7 100.5 89.0% Example 3 150.3 103.7 89.7% Example 4 152.9 107.1 91.3% Comparative Example 1 148.4 89.0 75.1% Comparative Example 2 147.9 90.2 83.1% Comparative Example 3 146.8 85.0 80.7% Comparative Example 4 145.5 82.9 79.6%

[0079] As can be seen from Table 1, the rate performance and cycle performance at 1C of the batteries assembled with the cathode materials of each embodiment are better than those of the comparative example, especially the cycle stability, which is greatly improved. A comparison between Example 4 and Comparative Example 1 shows that the use of single-crystal O3 phase NaNi... 1 / 3 Fe 1 / 3 Mn 1 / 3 Batteries prepared with O2-based cathode modification materials exhibit improved capacity utilization, rate performance, and cycle stability compared to polycrystalline O3-phase NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 The O2 content was improved. Comparative Examples 2-4 used single-crystal O3 phase NaNi. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 material is used as the modified matrix, but it lacks Zr dopant. 4+ Or MOF-808, Na3Zr2Si2PO 12 The co-coating treatment method cannot achieve optimal results in terms of capacity utilization, rate performance, and cycle stability of the prepared batteries. This demonstrates that using single-crystal O3 phase NaNi... 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 is the matrix, doped with Zr. 4+ MOF-808 and Na3Zr2Si2PO 12 The co-coating of these two processes improves the yield of single-crystal O3 phase NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2-based cathode modification materials have synergistic effects on capacity utilization, rate performance, and cycle stability.

[0080] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0082] The present invention has been illustrated with the above embodiments to describe the detailed process flow of the present invention. However, the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a sodium-ion battery cathode modification material, characterized in that, Comprising the following steps: A nickel source, a manganese source and an iron source are provided to prepare a transition metal oxide precursor, and the transition metal oxide precursor is sintered with a sodium salt to prepare a single crystal NaNi x Fe y Mn z O2 material, 0.2≤x≤0.4, 0.1≤y≤0.4, 0.2≤z≤0.4, and the single crystal NaNi x Fe y Mn z O2 material is obtained by ion doping and co-coating treatment to obtain a sodium ion battery positive electrode modification material.

2. The method for preparing sodium-ion battery cathode modification material according to claim 1, characterized in that, The ions of the ion doping process include Zr 4+ , Ti 4+ , Al 3+ , Cu 2+ , Zn 2+ , Mg 2+ .

3. The method for preparing sodium-ion battery cathode modification material according to claim 2, characterized in that, The incorporation amount of Zr 4+ , Ti 4+ , Al 3+ , Cu 2+ , Zn 2+ , Mg 2+ is 1-3% of the amount of substance of Na x Fe y Mn z in O2 + .

4. The method for preparing sodium-ion battery cathode modification material according to claim 1, characterized in that, The co-coating material comprises MOF-808, NU-1000, NU-901, DUT-67(Zr), PCN-777, UiO-66, Na 1+x Zr2Si x P 3-x O 12 (0≤x≤3), NaZr2(PO4)3, NaTi2(PO4)3, or NaGe2(PO4)3.

5. The method for preparing the sodium-ion battery cathode modification material as described in claim 1, characterized in that, The amount of the co-coating material is 0.05-0.2wt% of the single crystal NaNi x Fe y Mn z O2material mass.

6. The method for preparing the sodium-ion battery cathode modification material as described in claim 1, characterized in that, The single crystal NaNi x Fe y Mn z The ion doping and co-coating treatment of the O2 material includes: Single crystal NaNi x Fe y Mn z O2 materials with the source of heteroion, co-coated materials in O2 atmosphere, 300-500℃, the heating rate is 1-5℃ / min, sintering 6-12h and grinding.

7. The method for preparing sodium-ion battery cathode modification material according to claim 6, characterized in that, At least one of the following conditions is met: The heteroion source is a zirconium source; The zirconium source is Zr(NO3)4·5H2O, ZrO2 or ZrF4; The single crystal NaNi x Fe y Mn z O2 material, a source of a heteroion, a co-coating material in a mass ratio of 100:7-10:0.2-1.

8. The method for preparing the sodium-ion battery cathode modification material as described in claim 1, characterized in that, The single crystal NaNi x Fe y Mn z The preparation process of the O2 material comprises: (1) The nickel source, iron source and manganese source are added to deionized water to form an aqueous solution, then a chelating agent and a dispersing agent are added and stirred to form a transparent sol, which is heated at high temperature to obtain a polyethylene glycol lipid gel, and the transition metal oxide precursor is obtained after aging; (2) mixing the transition metal oxide precursor and sodium salt, pre-sintering under O2 atmosphere, and then sintering to obtain single crystal NaNi x Fe y Mn z O2 material; The nickel source is selected from one or more of nickel acetate, nickel sulfate, nickel chloride and nickel nitrate; The manganese source is selected from one or more of manganese acetate, manganese sulfate, manganese chloride and manganese nitrate; The iron source is selected from one or more of ferrous sulfate, ferrous chloride and ferric nitrate; The sodium salt is selected from one or more of sodium carbonate, sodium bicarbonate and sodium hydroxide.

9. A sodium-ion battery cathode modification material, characterized in that, The positive electrode modification material of the sodium ion battery is prepared by the preparation method of any one of claims 1-8. The positive electrode modification material of the sodium ion battery is prepared by the preparation method of any one of claims 1-8.

10. The sodium-ion battery cathode modification material of claim 9, wherein, The sodium-ion battery cathode modification material comprises single-crystal O3-phase NaNi x Fe y Mn z O2matrix and a co-coating layer, the co-coating layer coating the matrix, the NaNi x Fe y Mn z O2matrix doped with Zr 4+ , Ti 4+ , Al 3+ , Cu 2+ , Zn 2+ , Mg 2+ .