Sodium-ion battery P2 / O3 composite phase layered oxide positive electrode material and preparation method thereof

Abstract

The invention discloses a P2 / O3 composite phase layered oxide positive electrode material and a preparation method thereof, the chemical formula of the sodium ion battery positive electrode material is NaaNixFeyMnzMbO2, 0.2 < = x < = 0.4, 0.05 < = y < = 0.2, 0.3 < = z < = 0.6, 0.7 < = a < = 0.9, 0.01 < = b < = 0.2, and M is any one or a combination of more of Li, Mg, Ti and Al elements. Appropriate elements and regulation and control proportions are screened through cation potential calculation, the P2 / O3 composite phase layered oxide positive electrode material is designed, and the characteristics of relatively high theoretical specific capacity and energy density of O3 phase layered oxide and good sodium ion diffusivity and structural stability of P2 phase are combined, so that the cycle performance and electrochemical characteristics of the material under high voltage are improved; and the capacity and the cycling stability of the material are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of sodium-ion battery cathode materials, specifically relating to a P2 / O3 composite phase layered oxide cathode material and its preparation method. Background Technology

[0002] With the continuous rise in global energy demand and increasing environmental awareness, the development of efficient, environmentally friendly, and safe energy storage systems has become particularly important. Sodium-ion batteries, due to the abundance and low cost of sodium resources and their superior safety performance, are considered a potential alternative to lithium-ion batteries and have received extensive research attention. However, sodium-ion batteries still face many bottlenecks in performance improvement and commercialization, especially in enhancing the performance of cathode materials. Layered oxides, as commonly used cathode materials in sodium-ion batteries, occupy a central position in related research due to their high reversible capacity and relatively simple synthesis process.

[0003] Layered oxides are mainly classified into two common types: P2 and O3. O3-phase layered oxides, with their high theoretical specific capacity, exhibit excellent energy density potential and are considered promising candidate materials for industrial applications. However, during charge-discharge at higher operating voltages (voltage > 4V), further sodium ion extraction occurs, leading to a more complex irreversible phase transition. This phase transition not only damages the crystal structure of the material but also causes significant interfacial side reactions, resulting in decreased cycle stability. Combining the good sodium ion diffusion and structural stability of the P2 phase, P2 / O3 composite layered oxides can be designed to further improve the cycling performance and electrochemical characteristics of the material under high voltage.

[0004] In recent years, P2 / O3 composite layered oxides have been extensively studied in sodium-ion batteries. Zhao et al. proposed the concept of "cation potential" and applied it to the directional design of P2 and O3 materials (Science 2020, 370, 708-711). Summary of the Invention

[0005] In view of the above-mentioned problems in the prior art, the purpose of this invention is to provide a sodium-ion battery P2 / O3 composite phase layered oxide cathode material and its preparation method. The core of this invention is that the P2 / O3 composite phase layered oxide cathode material can be controllably designed by means of the cation potential, so that it has better cycle performance and electrochemical characteristics.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A sodium-ion battery P2 / O3 composite phase layered oxide cathode material, wherein the chemical formula of the sodium-ion battery cathode material is NaaNixFeyMnzMbO2, wherein 0.2≤x≤0.4, 0.05≤y≤0.2, 0.3≤z≤0.6, 0.7≤a≤0.9, 0.01≤b≤0.2, and M is selected from any one or more combinations of Li, Mg, Ti, and Al elements.

[0007] Furthermore, the particle size of the sodium-ion battery P2 / O3 composite phase layered oxide cathode material is 2~10 μm.

[0008] A method for preparing a P2 / O3 composite phase layered oxide cathode material for sodium-ion batteries includes the following steps: (1) The nickel source, iron source, manganese source, M source and sodium source are crushed and mixed by a planetary ball mill to obtain the precursor; (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere; (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery P2 / O3 composite layered oxide.

[0009] Furthermore, the nickel source, iron source, and manganese source are selected from one or more of the corresponding oxides, carbonates, or metal powders. Furthermore, the sodium source includes any one or more combinations of sodium carbonate, sodium bicarbonate, sodium hydroxide, or sodium nitrate.

[0010] Furthermore, the M source includes any one or more combinations of Li, Mg, Ti, and Al.

[0011] Furthermore, the mixing time using a planetary ball mill is 1~24h, and the rotation speed is 100~1000 rpm.

[0012] Furthermore, the calcination temperature is 800~1000 ℃, the sintering time is 5~18 h, and the heating rate is 1~5 ℃ / min.

[0013] This invention provides a P2 / O3 composite phase layered oxide cathode material prepared by the above preparation method.

[0014] This invention provides the use of a P2 / O3 composite phase layered oxide cathode material in the preparation of cathode materials for sodium-ion batteries.

[0015] The present invention also includes the use of P2 / O3 composite phase layered oxide cathode material to prepare the cathode of sodium-ion battery, and the testing of its electrochemical performance.

[0016] Regarding the application of P2 / O3 composite phase layered oxide cathode material in the preparation of sodium-ion battery cathode material: After uniformly mixing P2 / O3 composite phase layered oxide cathode material with conductive agent and binder, the mixture is coated onto aluminum foil, and the aluminum foil is placed in a vacuum oven to dry. The dried foil is then cut into circular electrode sheets of appropriate diameter for use in the manufacture of sodium-ion coin cells.

[0017] Regarding the use of P2 / O3 composite phase layered oxide cathode material in the preparation of sodium-ion batteries, its electrochemical performance was tested: The P2 / O3 composite phase layered oxide cathode material, conductive carbon black, and PVDF binder prepared in this invention were weighed at a mass ratio of 8:1:1. First, the cathode material and conductive agent Super-P were weighed at a mass ratio of 8:1 and mixed evenly in a mortar. Then, the mixture was placed with the binder PVDF in an appropriate amount of NMP solvent and stirred to form a homogeneous slurry. The slurry was uniformly coated onto an Al foil current collector using a scraper. After drying, it was cut to serve as the cathode, and a sodium sheet as the anode. The electrolyte was 1 M NaFP6EC-DEC@5% FEC (1:1, V / V). A sodium coin cell was prepared, and its electrochemical performance was tested.

[0018] The beneficial effects of this invention are: (1) The P2 / O3 composite phase layered oxide cathode material prepared by the present invention is designed by screening suitable elements and adjusting the ratio through cation potential calculation.

[0019] (2) This invention innovatively prepares a P2 / O3 composite phase layered oxide cathode material, which combines the high theoretical specific capacity and energy density of O3 phase layered oxide with the good sodium ion diffusion and structural stability of P2 phase, thereby improving the cycle performance and electrochemical characteristics of the material under high voltage. Attached Figure Description

[0020] Figure 1 The X-ray diffraction pattern is shown for the sample prepared in Example 1.

[0021] Figure 2 The graph shows the rate performance of the sodium-ion button battery assembled from the sample prepared in Example 1.

[0022] Figure 3 The graph shows the cycle performance of the sodium-ion button battery assembled from the sample prepared in Example 1. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The following specific embodiments or drawings are used to illustrate the present invention, but are not intended to limit the scope of the invention. Example 1

[0024] (1) The nickel oxide: iron oxide: manganese trioxide: lithium hydroxide: titanium dioxide: copper oxide: aluminum oxide: sodium carbonate = 0.25: 0.025: 0.25: 0.05: 0.06: 0.03: 0.025: 0.425 was crushed and mixed by a planetary ball mill. The mixing time of the planetary ball mill was 12 hours and the speed was 300 rpm.

[0025] (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere at a calcination temperature of 950 °C for 12 h with a heating rate of 5 °C / min.

[0026] (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery P2 / O3 composite layered oxide.

[0027] (4) The target product prepared above is used as the positive electrode active material and weighed with conductive carbon black and PVDF binder at a mass ratio of 8:1:1. First, the positive electrode material and conductive agent Super-P are weighed at a mass ratio of 8:1. After being mixed evenly in a slurry mixer, PVDF binder and an appropriate amount of NMP solvent are added and stirred in the slurry mixer to obtain a homogeneous slurry. The slurry is uniformly coated on Al foil current collector with a scraper and vacuum dried at 120 °C for 12 h. After drying, it is cut into circular electrode sheets to obtain sodium-ion battery positive electrode sheets for button cells.

[0028] (5) The above electrode sheet is used as the positive electrode, the sodium sheet is used as the negative electrode, and the electrolyte is 1M NaPF6EC-DEC@5% FEC (1:1, V / V). The CR2032 button cell is assembled in the order of positive electrode sheet, separator, sodium sheet, gasket and spring sheet. The packaged battery is left to stand for 12 h to allow the electrodes to be fully wetted by the electrolyte for subsequent electrochemical performance testing.

[0029] The P2 / O3 composite layered oxide cathode material prepared in Example 1 has a discharge specific capacity of 133.6 mAh / g at a current density of 0.1C within a voltage range of 2-4.2 V, and a reversible specific capacity of 107.6 mAh / g at 1C. It also exhibits excellent cycle stability, with a capacity retention rate of up to 94.2% after 100 cycles at 1C.

[0030] The X-ray diffraction pattern of the cathode material sample prepared in this embodiment is as follows: Figure 1 As shown.

[0031] The rate performance of the sodium-ion button cell obtained from the cathode material sample prepared in this embodiment is as follows: Figure 2 As shown.

[0032] The cycle performance of the sodium-ion button cell of the cathode material sample prepared in this embodiment is as follows: Figure 3 As shown. Comparative Example 1

[0033] Comparative Example 1 is a pure O3 phase, and its preparation process is as follows: (1) Nickel oxide, iron oxide, manganese trioxide and sodium carbonate are crushed and mixed by a planetary ball mill. The mixing time of the planetary ball mill is 12 hours and the speed is 300 rpm.

[0034] (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere at a temperature of 890 °C for 12 h with a heating rate of 5 °C / min.

[0035] (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery O3 phase layered oxide.

[0036] (4) The electrode fabrication and electrochemical testing were similar to those in Example 1. Example 2

[0037] (1) The nickel oxide: iron oxide: manganese trioxide: lithium carbonate: titanium dioxide: copper oxide: aluminum oxide: sodium hydroxide = 0.25: 0.025: 0.25: 0.025: 0.07: 0.01: 0.025: 0.85 was crushed and mixed by a planetary ball mill. The mixing time of the planetary ball mill was 8 hours and the speed was 1000 rpm.

[0038] (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere at a temperature of 900 °C for 18 h with a heating rate of 5 °C / min.

[0039] (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery P2 / O3 composite layered oxide.

[0040] (4) The electrode fabrication and electrochemical testing were similar to those in Example 1. Example 3

[0041] (1) The molar ratio of nickel oxide: iron oxide: manganese dioxide: lithium hydroxide: titanium dioxide: copper oxide: aluminum oxide: sodium bicarbonate = 0.25: 0.025: 0.25: 0.01: 0.06: 0.05: 0.025: 0.415 was crushed and mixed by a planetary ball mill. The mixing time of the planetary ball mill was 24 hours and the speed was 500 rpm.

[0042] (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere at a calcination temperature of 980 ℃ for 9 h and a heating rate of 2 ℃ / min.

[0043] (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery P2 / O3 composite layered oxide.

[0044] (4) The electrode fabrication and electrochemical testing were similar to those in Example 1. Example 4

[0045] (1) The molar ratio of nickel oxide: iron oxide: manganese dioxide: lithium carbonate: titanium dioxide: copper oxide: aluminum oxide: sodium nitrate = 0.25: 0.025: 0.25: 0.005: 0.08: 0.01: 0.025: 0.85 was crushed and mixed by a planetary ball mill. The mixing time of the planetary ball mill was 18 hours and the speed was 800 rpm.

[0046] (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere at a calcination temperature of 850 °C for 8 h and a heating rate of 1 °C / min.

[0047] (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery P2 / O3 composite layered oxide.

[0048] (4) The electrode fabrication and electrochemical testing were similar to those in Example 1. Example 5

[0049] (1) The molar ratio of nickel oxide: iron oxide: manganese dioxide: lithium carbonate: titanium dioxide: copper oxide: aluminum oxide: sodium carbonate = 0.25: 0.025: 0.25: 0.01: 0.06: 0.02: 0.035: 0.415 was used to crush and mix the materials by a planetary ball mill. The mixing time of the planetary ball mill was 18 hours and the speed was 800 rpm.

[0050] (2) The precursor obtained after grinding in step (1) is calcined in a tube furnace under an oxygen atmosphere at a calcination temperature of 850 °C for 8 h and a heating rate of 1 °C / min.

[0051] (3) The product after calcination in step (2) is ground and dispersed in a mortar to obtain a sodium-ion battery P2 / O3 composite layered oxide.

[0052] (4) The electrode fabrication and electrochemical testing were similar to those in Example 1.

[0053] Table 1 shows the electrochemical performance of the materials obtained in each embodiment.

[0054] The results of Example 1 and Comparative Example 1, as shown in the table above, demonstrate that P2 / O3 composite layered oxide cathode materials can be designed using cation potential calculations. Although the resulting materials exhibit some capacity loss, they show a significant improvement in cycle life, with a 0.1C discharge specific capacity of 133.6 mAh g⁻¹. -1 The specific capacity of 1C is 107.6mAh g. -1 The capacity retention rate after 100 cycles is as high as 94.2%. Based on the results of Examples 1-5, it can be seen that the design ratio of Example 1 has the best performance.

[0055] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A sodium-ion battery P2 / O3 composite phase layered oxide cathode material, characterized in that, The chemical formula of the sodium ion battery cathode material is Na a Ni x Fe y Mn z M b O2, wherein, 0.2≤x≤0.4, 0.05≤y≤0.2, 0.3≤z≤0.6, 0.7≤a≤0.9, 0.01≤b≤0.2, M is selected from any one or a combination of multiple of Li, Mg, Ti, Al elements.

2. The sodium-ion battery P2 / O3 composite phase layered oxide cathode material of claim 1, wherein, The particle size of the sodium ion battery P2 / O3 composite phase layered oxide positive material is 2-10 microns.

3. A method of producing a sodium-ion battery P2 / O3 composite phase layered oxide cathode material as claimed in claim 1 or 2, characterized in that, The method comprises the following steps: (1) crushing and mixing a nickel source, an iron source, a manganese source, an M source and a sodium source by a planetary ball mill to obtain a precursor; (2) calcining the precursor obtained after grinding in step (1) in a tube furnace under an oxygen atmosphere; (3) grinding and dispersing the product after calcination in step (2) in a mortar to obtain a sodium ion battery P2 / O3 composite phase layered oxide.

4. The method for preparing a sodium-ion battery P2 / O3 composite layered oxide cathode material according to claim 3, characterized in that, In step (1), the nickel source, the iron source and the manganese source are each selected from one or more of corresponding oxides, carbonates or metal powders.

5. The method for preparing a sodium-ion battery P2 / O3 composite layered oxide cathode material according to claim 3, characterized in that, In step (1), the sodium source includes any one or a combination of multiple of sodium carbonate, sodium bicarbonate, sodium hydroxide or sodium nitrate.

6. The method for preparing a sodium-ion battery P2 / O3 composite layered oxide cathode material according to claim 3, characterized in that, In step (1), the M source includes any one or a combination of multiple of Li, Mg, Ti and Al.

7. The method for preparing a sodium-ion battery P2 / O3 composite layered oxide cathode material according to claim 3, characterized in that, In step (1), the mixing time of the planetary ball mill is 1-24 hours, and the rotation speed is 100-2000 rpm.

8. A method for preparing a sodium-ion battery P2 / O3 composite layered oxide cathode material according to claim 3, characterized in that, In step (2), the calcination temperature is 800-1000 DEG C, the sintering time is 5-18 hours, and the temperature rising speed is 1-5 DEG C / min.

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