Double-modified layered oxide positive electrode material for sodium-ion battery and preparation method of double-modified layered oxide positive electrode material

Abstract

The invention belongs to the technical field of sodium-ion battery positive electrode material preparation, and particularly discloses a double-modified sodium-ion battery layered oxide positive electrode material and a preparation method thereof, and the preparation method comprises the following steps: S1, synthesizing a P2-type sodium-ion battery nickel-manganese-based layered oxide by using a high-temperature solid-phase method; s2, uniformly mixing two or more of lithium fluoride, sodium fluoride, calcium fluoride or magnesium fluoride in proportion to prepare a multi-element fluoride coating material; and S3, uniformly mixing the P2-type sodium-ion battery nickel-manganese-based layered oxide and the multi-fluoride coating material according to a ratio, and then carrying out high-temperature quenching treatment to obtain the surface fluoride-coated and near-bulk-phase-doped dual-modified sodium-ion battery layered oxide positive electrode material. According to the dual-modified layered oxide positive electrode material for the sodium-ion battery and the preparation method, surface fluoride coating and near bulk phase doping are cooperatively utilized, so that the high-voltage cycle performance of the layered oxide positive electrode material for the sodium-ion battery is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of cathode materials for sodium-ion batteries, and in particular to a double-modified layered oxide cathode material for sodium-ion batteries and a preparation method thereof. Background Art

[0002] Due to the abundance and low cost of sodium resources, sodium-ion batteries are expected to replace lithium-ion batteries in the fields of large-scale energy storage and low-speed electric vehicles. However, the low energy density of sodium-ion batteries limits their practical applications. The cathode material is the key to improving the energy density of sodium-ion batteries. Among many cathode materials for sodium-ion batteries, layered oxides (Na x TMO2, where TM represents transition metals) have the advantages of diverse compositions, simple preparation processes, relatively excellent performance, and environmental friendliness, and are the most promising cathode material types for rapid industrialization. The P2-type layered oxide has a unique trigonal prism sodium ion site that reduces the diffusion energy barrier during sodium ion migration, making the P2-type layered oxide have better rate performance. P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2, as a typical P2-type layered oxide cathode material for sodium-ion batteries, also has the advantages of high theoretical specific capacity (≈173 mAh / g), high working voltage (>3.6 V), and low cost, and has become one of the most promising cathode materials for practical applications. However, the high-voltage cycling performance of the P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 cathode material is poor, which limits its practical applications.

[0003] In the prior art, both the coating strategy and the doping strategy can improve the high-voltage cycling performance of the P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 cathode material to a certain extent. However, the coating strategy has no direct effect on the bulk phase, and the doping strategy also has a very limited effect on the surface interface. Simultaneously realizing the construction of the surface coating layer and the bulk phase ion doping can synergistically utilize the advantages of surface coating and bulk doping, and achieve a stable crystal structure and reversible redox of lattice oxygen while constructing a stable and efficient electrode-electrolyte interface, thereby improving the cycling performance of the P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 cathode material. Since the Gibbs free energy of formation of fluoride is relatively low, fluoride is very stable. In addition, fluoride is also more resistant to moisture in the surrounding air than oxide, which is very beneficial for improving the air stability of layered oxides. Summary of the Invention

[0004] The object of the present invention is to provide a double-modified layered oxide cathode material for sodium-ion batteries and a preparation method thereof, which synergistically utilize surface fluoride coating and near-bulk doping to improve the high-voltage cycling performance of the layered oxide cathode material for sodium-ion batteries.

[0005] To achieve the above object, the present invention provides a preparation method of a double-modified layered oxide cathode material for sodium-ion batteries, comprising the following steps: S1. Synthesize a P2-type nickel-manganese-based layered oxide for sodium-ion batteries by a high-temperature solid-phase method; S2. Mix two or more of lithium fluoride, sodium fluoride, calcium fluoride or magnesium fluoride in proportion to prepare a multi-component fluoride coating material; S3. Mix the P2-type nickel-manganese-based layered oxide for sodium-ion batteries obtained in S1 with the multi-component fluoride coating material obtained in S2 evenly, and then perform high-temperature quenching treatment to obtain a double-modified layered oxide cathode material for sodium-ion batteries with surface fluoride coating and near-bulk doping.

[0006] Preferably, S1 is specifically as follows: Mix sodium carbonate, nickel oxide and manganese oxide evenly by ball milling in proportion to obtain a precursor powder, tablet the precursor powder, and calcine it to obtain a P2-type nickel-manganese-based layered oxide for sodium-ion batteries with the chemical formula Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2.

[0007] Preferably, the mass ratio of the sodium carbonate, the nickel oxide and the manganese oxide is 2.226:1.471:3.174.

[0008] Preferably, the calcination temperature is 900 °C and the time is 12 hours.

[0009] Preferably, in S2, the multi-component fluoride coating material is specifically one of a lithium fluoride and calcium fluoride binary fluoride coating material with a molar ratio of 1:4, a sodium fluoride and calcium fluoride binary fluoride coating material with a molar ratio of 1:2, and a lithium fluoride, calcium fluoride and magnesium fluoride ternary fluoride coating material with a molar ratio of 0.59:0.279:0.131.

[0010] Preferably, S3 is specifically as follows: Mix the P2-type nickel-manganese-based layered oxide for sodium-ion batteries obtained in S1 with the lithium fluoride and calcium fluoride binary fluoride coating material evenly, and then calcine it at 800-900 °C for 15-120 minutes and then rapidly cool it in air to obtain a double-modified layered oxide cathode material for sodium-ion batteries with surface fluoride coating and near-bulk doping.

[0011] Preferably, S3 is specifically as follows: Mix the P2-type sodium-ion battery nickel-manganese-based layered oxide obtained in S1 with the sodium fluoride and calcium fluoride binary fluoride coating material evenly, and then calcine at 850 - 900 °C for 15 - 120 minutes and then rapidly cool in air to obtain a double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-bulk doping.

[0012] Preferably, S3 is specifically: Mix the P2-type sodium-ion battery nickel-manganese-based layered oxide obtained in S1 with the lithium fluoride, calcium fluoride, and magnesium fluoride ternary fluoride coating material evenly, and then calcine at 700 - 900 °C for 15 - 120 minutes and then rapidly cool in air to obtain a double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-bulk doping.

[0013] Preferably, in S3, the mass ratio of the P2-type sodium-ion battery nickel-manganese-based layered oxide to the multi-component fluoride coating material is 100:0 - 3.

[0014] The present invention also provides a double-modified sodium-ion battery layered oxide cathode material.

[0015] Therefore, by adopting the above-mentioned double-modified sodium-ion battery layered oxide cathode material and preparation method, the beneficial effects of the present invention are as follows: (1) The present invention utilizes the high stability of fluoride and its advantage of being able to resist the erosion of moisture in the surrounding air, and synchronously realizes the surface fluoride coating and near-bulk multi-element doping of the P2-type sodium-ion battery nickel-manganese-based layered oxide cathode material through high-temperature quenching treatment, synergistically utilizing the advantages of surface coating and near-bulk doping, while constructing a stable and efficient electrode-electrolyte interface, realizing a stable crystal structure and reversible lattice oxygen redox. Specifically, on the one hand, the surface fluoride can inhibit the interfacial side reaction, and on the other hand, it can inhibit the oxygen release; on the one hand, the near-phase body with multi-element co-doping can inhibit the structural degradation, and on the other hand, it has excellent Na + diffusion kinetics, thereby improving the high-voltage cycling performance of the battery.

[0016] (2) The preparation process adopted by the present invention is simple, has low energy consumption, low production cost, and the processing volume is flexibly variable, and has broad industrial application prospects. The technical solutions of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0017] Figure 1 is a schematic flow chart of an embodiment of a double-modified sodium-ion battery layered oxide cathode material and preparation method of the present invention; Figure 2XRD patterns of Examples 1-4 of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention; Figure 3 XRD patterns of Examples 5-8 of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention; Figure 4 XRD patterns of Examples 9-11 of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention; Figure 5 HRTEM images of Examples of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention, where (a) is Example 1 and (b) is Example 3; Figure 6 Cycling performance comparison diagrams of Examples 1-4 of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention; Figure 7 Cycling performance comparison diagrams of Examples 5-8 of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention; Figure 8 Cycling performance comparison diagrams of Examples 9-11 of the dual-modified layered oxide cathode material for sodium-ion batteries and its preparation method according to the present invention. Detailed implementation manners

[0018] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and examples.

[0019] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs. Unless otherwise specified, the materials used in the examples are prepared according to existing methods or directly purchased from the market.

[0020] The preparation method process of the dual-modified layered oxide cathode material for sodium-ion batteries obtained in the examples is schematically shown as Figure 1 shown.

[0021] Example 1 A dual-modified layered oxide cathode material for sodium-ion batteries, and its preparation method is as follows: S1. Mix sodium carbonate, nickel oxide and manganese oxide powders with a mass ratio of 2.226:1.471:3.174 by ball milling to obtain a precursor powder. Press the precursor powder into tablets and calcine in a muffle furnace at 900 °C for 12 hours to obtain P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2.

[0022] S2. Mix lithium fluoride and calcium fluoride with a molar ratio of 1:4 by ball milling to obtain a binary fluoride coating material.

[0023] S3. Mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material in a mass ratio of 100:0, mix evenly, calcine in a muffle furnace at 800 °C for 15 minutes, and then rapidly cool in air to obtain a surface lithium fluoride and calcium fluoride coated and near-bulk Li + 、Ca 2+ and F - co-doped double-modified sodium-ion battery layered oxide cathode material, labeled as LCF-0.

[0024] Example 2 The difference from Example 1 is that in S3, mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material in a mass ratio of 100:1, mix evenly, and label it as LCF-1.

[0025] Example 3 The difference from Example 1 is that in S3, mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material in a mass ratio of 100:2, mix evenly, and label it as LCF-2.

[0026] Example 4 The difference from Example 1 is that in S3, mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material in a mass ratio of 100:3, mix evenly, and label it as LCF-3.

[0027] Example 5 A double-modified sodium-ion battery layered oxide cathode material, and its preparation method is as follows: S1. Mix sodium carbonate, nickel oxide, and manganese oxide powders with a mass ratio of 2.226:1.471:3.174 by ball milling to obtain a precursor powder. Press the precursor powder into tablets and calcine in a muffle furnace at 900 °C for 12 hours to obtain P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2.

[0028] S2. Mix sodium fluoride and calcium fluoride with a molar ratio of 1:2 by ball milling to obtain a binary fluoride coating material.

[0029] S3. Mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material evenly at a mass ratio of 100:0, calcine at 850 °C in a muffle furnace for 15 minutes, and then perform rapid air cooling to obtain a surface sodium fluoride and calcium fluoride coating and near-bulk Ca 2+ and F - co-doped double-modified layered oxide cathode material for sodium-ion batteries, labeled as NCF-0.

[0030] Example 6 The difference from Example 5 is that in S3, mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material evenly at a mass ratio of 100:1, labeled as NCF-1.

[0031] Example 7 The difference from Example 5 is that in S3, mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material evenly at a mass ratio of 100:2, labeled as NCF-2.

[0032] Example 8 The difference from Example 5 is that in S3, mix P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 and the binary fluoride coating material evenly at a mass ratio of 100:3, labeled as NCF-3.

[0033] Example 9 A double-modified layered oxide cathode material for sodium-ion batteries, and its preparation method is as follows: S1. Mix sodium carbonate, nickel oxide and manganese oxide powders with a mass ratio of 2.226:1.471:3.174 evenly by ball milling to obtain a precursor powder. Press the precursor powder into tablets and calcine at 900 °C in a muffle furnace for 12 hours to obtain P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2.

[0034] S2. Mix lithium fluoride, calcium fluoride and magnesium fluoride with a molar ratio of 0.59:0.279:0.131 evenly by ball milling to obtain a ternary fluoride coating material.

[0035] S3. Mix P2-Na 2 / 3 Ni 1 / 3 Mn2 / 3 O2 was mixed evenly with the ternary fluoride coating material in a mass ratio of 100:0, calcined in a muffle furnace at 700 °C for 15 minutes, and then rapidly cooled in air to obtain a double-modified layered oxide cathode material for sodium-ion batteries with surface lithium fluoride, calcium fluoride, and magnesium fluoride coating and near-bulk Li + , Ca 2+ , Mg 2+ and F - co-doped, marked as LCM-0.

[0036] Example 10 The difference from Example 9 is that in S3, P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 was mixed evenly with the ternary fluoride coating material in a mass ratio of 100:1, marked as LCM-1.

[0037] Example 11 The difference from Example 9 is that in S3, P2-Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2 was mixed evenly with the ternary fluoride coating material in a mass ratio of 100:2, marked as LCM-2.

[0038] Test and measurement The cathode materials prepared in Examples 1-11 were subjected to structural analysis. The XRD analysis results are as Figures 2 - 4 shown, and the HRTEM analysis results are as Figure 5 shown.

[0039] It can be seen from Figure 2 that a double-modified layered oxide cathode material for sodium-ion batteries with surface lithium fluoride and calcium fluoride coating and near-bulk Li + , Ca 2+ and F - co-doped was successfully prepared.

[0040] It can be seen from Figure 3 that a double-modified layered oxide cathode material for sodium-ion batteries with surface sodium fluoride and calcium fluoride coating and near-bulk Ca 2+ and F - co-doped was successfully prepared.

[0041] It can be seen from Figure 4 that a double-modified layered oxide cathode material for sodium-ion batteries with surface lithium fluoride, calcium fluoride, and magnesium fluoride coating and near-bulk Li + , Ca 2+ , Mg 2+ and F - co-doped was successfully prepared.

[0042] It can be seen from Figure 5 that there is no coating layer before modification, and there is a uniform coating layer on the surface of the layered oxide cathode material for sodium-ion batteries after double modification.

[0043] The button cells are assembled with the cathode materials prepared in Examples 1-11. The assembly process of the button cells is as follows: Using the cathode material prepared in the example as the cathode, sodium metal as the anode, and glass fiber (Whatman) as the separator, the button cells are assembled in a glove box.

[0044] The high-voltage cycling performance of the button cells is tested, and the test results are as Figures 6 - 8 shown.

[0045] It can be seen from Figure 6 , Figure 7 and Figure 8 that the double-modified layered oxide cathode material for sodium-ion batteries with surface fluoride coating and near-bulk doping exhibits better high-voltage cycling performance than the unmodified layered oxide cathode material for sodium-ion batteries, and the optimal value reaches 90.2%.

[0046] Therefore, the present invention adopts the above-mentioned double-modified layered oxide cathode material for sodium-ion batteries and its preparation method, and synergistically utilizes surface fluoride coating and near-bulk doping to improve the high-voltage cycling performance of the layered oxide cathode material for sodium-ion batteries.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preparation method of a double-modified layered oxide cathode material for a sodium-ion battery, characterized in that, It includes the following steps: S1. Synthesize P2-type sodium-ion battery nickel-manganese-based layered oxide by the high-temperature solid-state method; S2. Mix two or more of lithium fluoride, sodium fluoride, calcium fluoride or magnesium fluoride in proportion to prepare a multi-component fluoride coating material; S3. Mix the P2-type sodium-ion battery nickel-manganese-based layered oxide obtained in S1 with the multi-component fluoride coating material obtained in S2 evenly, and then perform high-temperature quenching treatment to obtain a double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-body phase doping.

2. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 1, characterized in that, Specifically, S1 is as follows: Proportionally, sodium carbonate, nickel oxide, and manganese oxide are ball-milled and mixed evenly to obtain a precursor powder. The precursor powder is tableted and calcined to obtain a P2-type sodium-ion battery nickel-manganese-based layered oxide with the chemical formula Na 2 / 3 Ni 1 / 3 Mn 2 / 3 O2.

3. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 2, characterized in that, The mass ratio of the sodium carbonate, the nickel oxide and the manganese oxide is 2.226:1.471:3.

174.

4. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 2, characterized in that, The calcination temperature is 900 °C and the time is 12 hours.

5. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 1, characterized in that, In S2, the multi-component fluoride coating material is specifically one of a lithium fluoride and calcium fluoride binary fluoride coating material with a molar ratio of 1:4, a sodium fluoride and calcium fluoride binary fluoride coating material with a molar ratio of 1:2, and a lithium fluoride, calcium fluoride and magnesium fluoride ternary fluoride coating material with a molar ratio of 0.59:0.279:0.

131.

6. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 5, characterized in that, Specifically, S3 is as follows: Mix the P2-type sodium-ion battery nickel-manganese-based layered oxide obtained in S1 with the lithium fluoride and calcium fluoride binary fluoride coating material evenly, and then calcine at 800-900 °C for 15-120 minutes and then quickly cool in air to obtain a double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-body phase doping.

7. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 5, characterized in that, Specifically, S3 is as follows: Mix the P2-type sodium-ion battery nickel-manganese-based layered oxide obtained in S1 with the sodium fluoride and calcium fluoride binary fluoride coating material evenly, and then calcine at 850-900 °C for 15-120 minutes and then quickly cool in air to obtain a double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-body phase doping.

8. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 5, characterized in that, Specifically, S3 is as follows: Mix the P2-type sodium-ion battery nickel-manganese-based layered oxide obtained in S1 with the lithium fluoride, calcium fluoride and magnesium fluoride ternary fluoride coating material evenly, and then calcine at 700-900 °C for 15-120 minutes and then quickly cool in air to obtain a double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-body phase doping.

9. The preparation method of a double-modified layered oxide cathode material for a sodium-ion battery according to claim 1, characterized in that, In S3, the mass ratio of the P2-type sodium-ion battery nickel-manganese-based layered oxide to the multi-component fluoride coating material is 100:0-3.

10. A double-modified sodium-ion battery layered oxide cathode material with surface fluoride coating and near-body phase doping prepared by the preparation method of the double-modified sodium-ion battery layered oxide cathode material according to any one of claims 1-9.

Images