Silicate doped P2 phase layered positive electrode material and preparation method and application thereof

Abstract

The invention belongs to the technical field of nano materials and electrochemistry, and particularly relates to a SiO3 < 2->-doped P2-phase Na < 0.67 > Ni < 0.33 > Mn < 0.67 > O2 layered positive electrode material Na < 0.67 > Ni < 0.33 > Mn < 0.67 > O2Six (x is greater than or equal to 0.005 and less than or equal to 0.05) (NNMO-Si) and a preparation method and application thereof. The material is formed by lamellar structures composed of particles in a layer-by-layer lap joint mode, and the diameter of the lamellar structures is about 1-2 microns. The NNMO-Si layered electrode material is successfully prepared through a simple sol-gel method and a high-temperature sintering method, and when the material is used as a sodium ion battery positive electrode active material, the material shows excellent rate capability and relatively excellent cycling stability, and is a potential application material of a high-power and long-life sodium ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nanomaterials and electrochemistry, and particularly relates to a silicate-doped P2 phase layered positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] In today's society, the application of lithium ion batteries in large-scale energy storage is limited due to the scarcity and high price of lithium resources, so it is urgent to explore new battery energy storage systems. Sodium ion batteries (SIBs) are expected to become the next generation of large-scale energy storage devices due to the abundance of sodium resources, low price, and similar working principles to lithium ion batteries. Developing positive electrode materials with high energy density, high safety, and long cycle life is the key to determining whether sodium ion batteries can be applied in commercial applications. However, Na + The relatively heavy molar mass and large ionic radius (1.06 Å) usually lead to large volume expansion and slow transport kinetics, resulting in poor cycle performance and poor rate performance, which limits their practical application. Therefore, it is urgent to explore high-performance electrode materials.

[0003] With further research, scientists have found that transition metal layered oxide positive electrode materials are considered one of the most promising positive electrode materials for sodium ion batteries due to their simple preparation method, green safety, high capacity, and high voltage. Among the transition metal layered oxide positive electrode materials, P2 phase Na 0.67 Ni 0.33 Mn 0.67 O2 layered positive electrode material (P2-NNMO) has advantages such as high rate performance, less phase transition, good air stability, and has been favored by researchers. However, P2-NNMO layered positive electrode material has the following problems: when discharged to a low voltage, Mn 4+ is reduced to Mn 3+ , and the Jahn-Teller effect of Mn 3+ affects the structural stability of the material; during the electrochemical charging and discharging process, the vacancy-ordered rearrangement of interlayer sodium ions occurs, and the P2-O2 phase transition of the material at high pressure occurs, which leads to poor cycle stability and low sodium ion migration rate of the material, which seriously affects the electrochemical performance of the P2-NNMO layered positive electrode material. Researchers currently mainly focus on the phase transition of the material at high pressure, which leads to poor cycle performance, and have conducted a lot of research, ignoring the poor electrochemical performance of the material at low pressure. Therefore, it is an indispensable part of the research to modify P2-NNMO layered positive electrode material by simple element doping to improve the electrochemical performance of the material at low pressure. SUMMARY

[0004] The technical problem to be solved by the present application is to design a P2-NNMO layered positive electrode material with appropriate SiO3 2- The preparation method of the anion group has simple process and short operation period, so that the method has great potential for large-scale industrialization, and the obtained NNMO-Si material has very excellent electrochemical performance at low pressure.

[0005] A preparation method of a silicate doped P2 phase layered positive electrode material, comprising the following steps: S1, citric acid monohydrate, silicon source and transition metal are uniformly dissolved in a solvent to obtain a mixed solution; wherein the transition metal is a mixture of manganese source and nickel source; S2, the mixed solution is sequentially subjected to stirring, drying, grinding and calcination treatment to obtain a powder material; S3, sodium source is added to the powder material, and the powder material is sequentially subjected to grinding and calcination treatment to obtain a silicate doped P2 phase layered positive electrode material.

[0006] Further, in step S1, citric acid monohydrate, manganese source, nickel source and silicon source are in stoichiometric ratio of 1.5:0.675:0.325:0.005~0.05.

[0007] Further, the manganese source is manganese nitrate tetrahydrate, and the concentration of the manganese source is 0.0536 mol·L -1 ; The nickel source is nickel nitrate hexahydrate, and the concentration of the nickel source is 0.0264 mol·L -1 ; The silicon source is sodium silicate, and the concentration of the silicon source is 0.0004~0.0040 mol·L -1 .

[0008] Further, in step S2, the stirring operation of the mixed solution is carried out at 60~80 ℃ oil bath condition, and the time condition is 5 h.

[0009] Further, in step S2, the drying temperature condition is 120~150 ℃, and the time condition is 12 h.

[0010] Further, in step S2, the calcination temperature condition is 450~550 ℃, and the time condition is 6~12 h.

[0011] Further, in step S3, the calcination treatment is specifically operated at 800~950 ℃ O2 atmosphere for 10~15 h, and the heating rate is 2 ℃·min -1 ; The grinding time condition is 20~40 min.

[0012] Further, in step S2, the sodium source is Na2CO3, and the sodium source: transition metal = 1.05 in stoichiometric ratio.

[0013] The silicate-doped P2 phase layered cathode material obtained by the preparation method.

[0014] Further, the general formula of the silicate-doped P2 phase layered cathode material is Na 0.67 Ni 0.32 Mn 0.67 O2Si x , wherein 0.005 <= x <= 0.05. x <= 0.05; The material is composed of a sheet-like structure layer formed by layer-by-layer lapping of particles, and the diameter of the sheet-like structure is about 1-2 microns.

[0015] Application of the silicate-doped P2 phase layered cathode material as a sodium ion battery cathode active material The beneficial effects of the present application are: (1) the NNMO-Si x material prepared by the present application has a large interlayer spacing and fast Na + insertion / extraction kinetics. In addition, the SiO3 2- anion group has a very stable coordination structure and a very high Si-O (798 kJ·mol -1 ) bond energy, which can stabilize the structure of the material and exhibit excellent rate performance and cycle stability in battery tests; (2) the present application successfully prepares a P2 phase NNMO-Si layered material by a simple sol-gel method and a high-temperature sintering method. The process of the present application is simple, the operation period is short, the synthesis method used has low requirements on equipment, and the material prepared has high purity, good dispersity, is easy to scale up, meets the characteristics of efficient chemistry, and is very beneficial to market promotion; (3) when used as a sodium ion battery cathode active material, the material exhibits excellent rate performance and relatively excellent cycle stability, and is a potential application material for high-power and long-life sodium ion batteries. The material was subjected to constant current charge and discharge tests at current densities of 17.3, 34.6, 86.5, 173.0, 346.0, 865.0 and 1730.0 mA / g, respectively, and the reversible discharge specific capacity was 161.5, 154.4, 140.1, 131.8, 118.2, 93.3 and 52.9 mAh / g, respectively, exhibiting excellent rate performance. In addition, the capacity of the material was as high as 76.6 mAh / g after 300 cycles at a current density of 173.0 mA / g, and the material had relatively excellent cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 XRD pattern of the material; Figure 2 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 SEM pattern of the material; Figure 3 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 EDS mapping pattern of the material; Figure 4 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 Cyclic voltammogram of the material at 0.1 mV·s -1 Scan rate; Figure 5 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 Rate performance pattern of the material; Figure 6 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 Battery cycle performance pattern of the material (a) and P2-NNMO (b) at 173 mA / g current density; Figure 7 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 Comparison pattern of sodium ion diffusion rate of P2-NNMO electrode material; Figure 8 P2 phase NNMO-Si of the embodiment 1 of the present application 0.01 Comparison pattern of initial state electrochemical impedance spectrum of P2-NNMO electrode. DETAILED DESCRIPTION

[0017] In order to better understand the present application, the content of the present application is further illustrated below in combination with embodiments, but the content of the present application is not limited to only the following embodiments.

[0018] In the present application, by introducing SiO3 2- Anion group in P2-NNMO layered positive electrode material, the problems of poor cycle stability at low pressure and low ion migration rate caused by vacancy ordering rearrangement of interlayer sodium ions in the charging and discharging process are improved, the conductivity of the material is improved and the redox kinetics of the material is accelerated.

[0019] Based on this, the first protection of the present application is a preparation method of a silicate doped P2 phase layered positive electrode material, comprising the following steps: 1) A certain amount of monohydrated citric acid, silicon source and transition metal are uniformly dissolved in 50 mL of deionized water to obtain a mixed solution; wherein the transition metal (TM) is a mixture of manganese source and nickel source; in terms of stoichiometric ratio, monohydrated citric acid: manganese source: nickel source: silicon source = 1.5: 0.67: 0.33: 0.005~0.05; 2) The manganese source is manganese nitrate tetrahydrate, and the concentration thereof in the solution is 0.0536 mmol·mL -1 ; The nickel source is nickel nitrate hexahydrate, and the concentration thereof in the solution is 0.02644 mmol·mL -1 ; The silicon source is sodium silicate, and the concentration thereof in the solution is 0.0004~0.0040 mmol·mL -1 ; 2) The solution obtained in step 1) is stirred at 60~80 ℃ under oil bath conditions for 5 h to obtain a jelly-like gel; 3) The jelly-like gel in step 2) is dried in an oven at 120~150 ℃ for 12 h to obtain a dry gel; 4) The dry gel obtained in step 3) is ground into powder and then placed in a muffle furnace for calcination at 450~550 ℃ for 6~12 h; 5) The powder obtained in step 4) is ground with Na2CO3 (Na2CO3: TM = 1.05) for 20~40 min, and then calcined at 800~950 ℃ under oxygen atmosphere for 10~15 h, with a heating rate of 2 ℃·min -1 , to obtain a silicate-doped P2-phase layered positive electrode material.

[0020] The second protection of the present application is a silicate-doped P2-phase layered positive electrode material, which has a general formula of Na 0.67 Ni 0.32 Mn 0.67 O2Si x , wherein 0.005≤ x ≤ 0.05, and the material is composed of a sheet-like structure layer formed by layer-by-layer lapping of particles, and the diameter of the sheet-like structure is about 1~2 μm.

[0021] The third protection of the present application is the application of the above-mentioned silicate-doped P2-phase layered positive electrode material as a positive electrode active material of a sodium ion battery.

[0022] <Comparative Example 1> A P2-phase Na 0.67 Ni 0.33 Mn 0.67 O2 (P2-NNMO) layered positive electrode material is prepared by the following steps: 1) Disperse 2.68 mmol manganese nitrate tetrahydrate, 1.32 mmol nickel nitrate hexahydrate, and 6 mmol citric acid monohydrate in 50 mL of deionized water and stir until homogeneous; 2) The solution obtained in step 1) was stirred in an oil bath at 70 °C for 5 h to obtain a jelly-like gel; 3) Place the jelly-like gel from step 2) in a 120 ℃ oven and dry for 12 h to obtain a dry gel; 4) Grind the dry gel obtained in step 3) into powder and calcine it in a muffle furnace at 450 °C for 6 h; 5) Add the powder obtained in step 4) to Na2CO3 (Na2CO3:TM = 1.05) according to the stoichiometric ratio, grind for 20 min, and then calcine at 900 ℃ in an O2 atmosphere for 12 h with a heating rate of 2 ℃·min. -1 P2-NNMO material was obtained.

[0023] Taking the product of this comparative example as an example, the material prepared by the sol-gel method is in the form of nanosheets with a relatively uniform particle size distribution, ranging from 1.5 to 2 μm, and no obvious particle aggregation was observed. Taking the P2-NNMO material prepared in this comparative example as a cathode material for sodium-ion batteries, the capacity after 300 cycles at a current density of 173 mA / g is only 45.9 mAh / g.

[0024] <Example 1> P2 phase NNMO-Si 0.01 The method for preparing the material includes the following steps: 1) Disperse 2.68 mmol manganese nitrate tetrahydrate, 1.32 mmol nickel nitrate hexahydrate, and 6 mmol citric acid monohydrate in 50 mL of deionized water, then add 0.04 mmol sodium silicate and stir until homogeneous; 2) The solution obtained in step 1) was stirred in an oil bath at 70 °C for 5 h to obtain a jelly-like gel; 3) Place the jelly-like gel from step 2) in a 120 ℃ oven and dry for 12 h to obtain a dry gel; 4) Grind the dry gel obtained in step 3) into powder and calcine it in a muffle furnace at 450 °C for 6 h; 5) Add the powder obtained in step 4) to Na2CO3 (Na2CO3:TM = 1.05) according to the stoichiometric ratio, grind for 20 min, and then calcine at 900 ℃ in an O2 atmosphere for 12 h with a heating rate of 2 ℃·min. -1 P2 phase NNMO-Si was obtained 0.01 (NNMO-Si) material.

[0025] Taking the NNMO-Si material obtained in this embodiment as an example, its structure was determined by X-ray diffraction. Figure 1 As shown, the X-ray diffraction (XRD) pattern indicates that the characteristic peaks of the NNMO-Si material can be well matched with the standard card (JCPDS: 54-0894) of the layered P2-NNMO crystal phase.

[0026] like Figure 2 As shown, field emission scanning electron microscopy (FESEM) tests revealed that the material consists of a layered structure composed of particles, with the diameter of the layered structure being approximately 1–2 μm.

[0027] like Figure 3 As shown, the EDS mapping diagram proves that the five elements O, Na, Si, Mn and Ni are distributed very uniformly in the P2 phase NNMO-Si material.

[0028] The layered NNMO-Si material prepared in this embodiment is used as the positive electrode active material for a sodium-ion battery. The remaining steps of the sodium-ion battery preparation method are the same as those in the prior art. The electrode sheet is prepared as follows: NNMO-Si material is used as the active material, acetylene black as the conductive agent, polyvinylidene fluoride as the binder, and N-methylpyrrolidone as the solvent. The mass ratio of the active material, acetylene black, and polyvinylidene fluoride is 7:2:1. After thoroughly mixing them in this ratio, they are uniformly coated onto aluminum foil, with an active material loading of 0.8~1.2 g cm⁻¹. -1 After drying in an oven at 65 °C for 12 h, the sample was cut into round slices using a slicer for later use. A coin cell sodium-ion battery was assembled using 1M NaClO4 dissolved in propylene carbonate (PC) as the electrolyte, a self-made sodium sheet as the counter electrode and reference electrode, glass fiber as the separator, and CR 2025 stainless steel as the battery casing.

[0029] Taking the NNMO-Si material prepared in this embodiment as an example as the positive electrode active material of a sodium-ion battery, such as Figure 4 As shown, this material at 0.1 mV s -1 Cyclic voltammetry tests were performed at a scanning speed of [value missing]. During the first charge, oxygen peaks were observed at 1.95, 2.33, 2.84, 3.18, 3.36, 3.66, and 3.72 V. Peaks below 2.0 V correspond to Mn [value missing]. 3+ / 4+ The redox couple. The broad peak in the potential range of 2.25–3.0 V corresponds to the ordered rearrangement of sodium ion vacancies in the interlayer of the material, and the broad peak in the potential range of 3.0–3.75 V corresponds to the redox couple of Ni. 2+ / 3+ / 4+The redox couple is well-formed. During the subsequent charge-discharge process, the CV curves almost overlap, indicating that the NNMO-Si layered electrode material exhibits excellent cycle reversibility.

[0030] like Figure 5 As shown, the material was subjected to constant current charge-discharge tests at current densities of 17.3, 34.6, 86.5, 173.0, 346.0, 865.0 and 1730 mA / g, respectively, and its reversible discharge specific capacity reached 161.5, 154.4, 140.1, 131.8, 118.2, 93.3 and 52.9 mAh / g, respectively, demonstrating excellent rate performance.

[0031] like Figure 6 As shown, the material exhibits a capacity of 76.6 mAh / g after 300 cycles at a current density of 173 mA / g, demonstrating excellent cycling stability.

[0032] like Figure 7 As shown, the differential capacity curves of NNMO-Si material at cycles 1, 50, and 100 clearly show a high degree of overlap, indicating excellent cycle stability. Electrochemical impedance spectroscopy (EIS) tests were performed on P2-NNMO and NNMO-Si materials.

[0033] like Figure 8 The charge transfer resistance of the NNMO-Si material shown R ct The value is 270.4 Ω, lower than that of P2-NNMO. R ct The lower charge transfer impedance (321.3 Ω) indicates that NNMO-Si material has better electronic conductivity. These properties demonstrate that NNMO-Si material possesses excellent fast-charging performance and relatively good cycle performance, making it a potential material for high-power, long-life sodium-ion batteries.

[0034] <Example 2> P2 phase NNMO-Si 0.005 The method for preparing the material includes the following steps: 1) Disperse 2.68 mmol manganese nitrate tetrahydrate, 1.32 mmol nickel nitrate hexahydrate, and 6 mmol citric acid monohydrate in 50 mL of deionized water, then add 0.02 mmol sodium silicate and stir until homogeneous; 2) The solution obtained in step 1) was stirred in an oil bath at 60 °C for 5 h to obtain a jelly-like gel; 3) Place the jelly-like gel from step 2) in a 120 ℃ oven and dry for 12 h to obtain a dry gel; 4) Grind the dry gel obtained in step 3) into powder and calcine it in a muffle furnace at 500 °C for 6 h; 5) Add the powder obtained in step 4) to Na2CO3 (Na2CO3:TM = 1.05) according to the stoichiometric ratio, grind for 30 min, and then calcine at 900 ℃ in an O2 atmosphere for 15 h with a heating rate of 2 ℃·min. -1 P2 phase NNMO-Si was obtained 0.005 Material.

[0035] P2 phase NNMO-Si prepared in this embodiment 0.005 Taking this material as an example of a positive electrode active material for sodium-ion batteries, it exhibits a capacity of up to 75.0 mAh / g after 300 cycles at a current density of 173 mA / g, demonstrating excellent cycle stability.

[0036] <Example 3> P2 phase NNMO-Si 0.015 The method for preparing the material includes the following steps: 1) Disperse 2.68 mmol manganese nitrate tetrahydrate, 1.32 mmol nickel nitrate hexahydrate, and 6 mmol citric acid monohydrate in 50 mL of deionized water, then add 0.06 mmol sodium silicate and stir until homogeneous; 2) The solution obtained in step 1) was stirred in an oil bath at 70 °C for 5 h to obtain a jelly-like gel; 3) Place the jelly-like gel from step 2) in an oven at 130 ℃ and dry for 12 h to obtain a dry gel; 4) Grind the dry gel obtained in step 3) into powder and calcine it in a muffle furnace at 550 °C for 6 h; 5) Add the powder obtained in step 4) to Na2CO3 (Na2CO3:TM = 1.05) according to the stoichiometric ratio, grind for 20 min, and then calcine at 900 ℃ in an O2 atmosphere for 12 h with a heating rate of 2 ℃·min. -1 Layered NNMO-Si was obtained 0.015 Material.

[0037] P2 phase NNMO-Si prepared in this embodiment 0.015 Taking this material as an example of a positive electrode active material for sodium-ion batteries, the material has a capacity of up to 79.8 mAh / g after 300 cycles at a current density of 173 mA / g, demonstrating excellent cycle stability.

[0038] <Example 4> P2 phase NNMO-Si 0.025 The method for preparing the material includes the following steps: 1) Disperse 2.68 mmol manganese nitrate tetrahydrate, 1.32 mmol nickel nitrate hexahydrate, and 6 mmol citric acid monohydrate in 50 mL of deionized water, then add 0.10 mmol sodium silicate and stir until homogeneous; 2) The solution obtained in step 1) was stirred in an oil bath at 80 °C for 5 h to obtain a jelly-like gel; 3) Place the gel from step 2) in a 150 ℃ oven and dry for 12 h to obtain a dry gel; 4) Grind the dry gel obtained in step 3) into powder and calcine it in a muffle furnace at 500 °C for 8 h; 5) Add the powder obtained in step 4) to Na2CO3 (Na2CO3:TM = 1.05) according to the stoichiometric ratio, grind for 30 min, and then calcine at 950 ℃ in an O2 atmosphere for 10 h with a heating rate of 2 ℃·min. -1 Layered P2 phase NNMO-Si was obtained 0.025 Material.

[0039] P2 phase NNMO-Si prepared in this embodiment 0.025 Taking this material as an example of a positive electrode active material for sodium-ion batteries, the material has a capacity of up to 75.9 mAh / g after 300 cycles at a current density of 173 mA / g, demonstrating excellent cycle stability.

[0040] <Example 5> P2 phase NNMO-Si 0.05 The method for preparing the material includes the following steps: 1) Disperse 2.68 mmol manganese nitrate tetrahydrate, 1.32 mmol nickel nitrate hexahydrate, and 6 mmol citric acid monohydrate in 50 mL of deionized water, then add 0.20 mmol sodium silicate and stir until homogeneous; 2) The solution obtained in step 1) was stirred in an oil bath at 70 °C for 5 h to obtain a jelly-like gel; 3) Place the gel from step 2) in an oven at 120~150 ℃ and dry for 12 h to obtain a dry gel. 4) Grind the dry gel obtained in step 3) into powder and calcine it in a muffle furnace at 450 °C for 6-12 h; 5) Add the powder obtained in step 4) to Na2CO3 (Na2CO3:TM = 1.05) according to the stoichiometric ratio, grind for 40 min, and then calcine at 900 ℃ in an O2 atmosphere for 12 h with a heating rate of 2 ℃·min. -1 Layered NNMO-Si was obtained 0.05 Material.

[0041] P2 phase NNMO-Si prepared in this embodiment 0.05 Taking this material as an example of a positive electrode active material for sodium-ion batteries, it exhibits a capacity of up to 78.6 mAh / g after 300 cycles at a current density of 173 mA / g, demonstrating excellent cycle stability.

[0042] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a silicate-doped P2 phase layered cathode material, characterized in that, Includes the following steps: S1. Citric acid monohydrate, silicon source, and transition metal are uniformly dissolved in a solvent to obtain a mixed solution; wherein the transition metal is a mixture of manganese source and nickel source; S2. The mixture is subjected to stirring, drying, grinding and calcination in sequence to obtain powder material; S3. Add sodium source to powder material, and after grinding and calcination, silicate-doped P2 phase layered cathode material can be obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, based on the stoichiometric ratio, citric acid monohydrate: manganese source: nickel source: silicon source = 1.5: 0.67: 0.33: 0.005~0.

05.

3. The method for preparing a silicate-doped P2 phase layered cathode material according to claim 2, characterized in that, The manganese source is manganese nitrate tetrahydrate, and the concentration of the manganese source is 0.0536 mmol·mL. -1 ; The nickel source is nickel nitrate hexahydrate, and the concentration of the nickel source is 0.0264 mmol·mL. -1 ; The silicon source is sodium silicate, and the concentration of the silicon source is 0.0004~0.0040 mmol·mL. -1 .

4. The method for preparing a silicate-doped P2-phase layered cathode material according to claim 1, characterized in that, In step S2, the stirring of the mixture is carried out in an oil bath at 60~80 ℃ for 5 h. The drying temperature conditions were 120~150 ℃, and the time conditions were 12 h.

5. The method for preparing a silicate-doped P2-phase layered cathode material according to claim 1, characterized in that, In step S2, the calcination temperature is 450~550 ℃ and the time is 6~12 h.

6. The method for preparing a silicate-doped P2-phase layered cathode material according to claim 1, characterized in that, In step S3, the calcination treatment specifically involves calcining at 800~950 ℃ in an O2 atmosphere for 10~15 h, with a heating rate of 2 ℃·min. -1 ; The grinding time is 20-40 min.

7. The method for preparing a silicate-doped P2-phase layered cathode material according to claim 1, characterized in that, In step S2, the sodium source is Na2CO3, and the stoichiometric ratio of sodium source to transition metal is 1.

05.

8. The silicate-doped P2 phase layered cathode material obtained by the preparation method according to any one of claims 1-7.

9. The silicate-doped P2-phase layered cathode material as described in claim 8, characterized in that, The general formula for silicate-doped P2 phase layered cathode materials is Na. 0.67 Ni 0.33 Mn 0.67 O2Si x , where 0.005≤ x ≤0.05; The material is composed of layers of lamellar structures made up of particles, with a diameter of approximately 1 to 2 μm.

10. The application of the silicate-doped P2 phase layered cathode material as described in claim 9 as a cathode active material for sodium-ion batteries.

Images