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CN-122025516-A - P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating and preparation method thereof

CN122025516ACN 122025516 ACN122025516 ACN 122025516ACN-122025516-A

Abstract

The invention discloses a preparation method of a P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating, which comprises the following steps of (1) weighing raw materials according to a stoichiometric formula Na 0.67 Ni 0.33‑ x Cu x Mn 0.67 O 2 , respectively dispersing the raw materials into distilled water, (2) sequentially and uniformly dispersing the dispersed solution into aqueous solution of citric acid, then stirring in a microwave reactor and heating at 100-110 ℃ until the solvent is completely evaporated to form green gel, grinding the gel into powder, presintering at 500-510 ℃, taking out and uniformly grinding again, then roasting at 950-1000 ℃ to obtain a roasting product, and (3) adding a C 4 H 6 MgO 4 ·4H 2 O solution into a roasting product suspension, stirring at 80-90 ℃ until the solvent is completely evaporated, and roasting the powder at 550-600 ℃ to obtain a product Na 0.67 Ni 0.33‑ x Cu x Mn 0.67 O 2 @ yMgO. The double modification strategy of combining partial substitution of crystal lattice with magnesium oxide (MgO) surface coating is carried out by copper ions (Cu 2+ ) so as to improve the structural stability, interface stability and dynamic performance of the material under the high-voltage condition.

Inventors

  • LIU QIBIN
  • HAN LINJUN
  • XU TENG
  • SHEN MIN
  • HUANG BINGBING

Assignees

  • 贵州大学

Dates

Publication Date
20260512
Application Date
20260130

Claims (8)

  1. 1. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating is characterized by comprising the following steps: (1) Weighing CH 3 COONa、 NiC 4 H 6 O 4 ·4H 2 O、MnC 4 H 6 O 4 ·4H 2 O、C 4 H 6 CuO 4 ·H 2 O, according to the stoichiometric amount of Na 0.67 Ni 0.33-x Cu x Mn 0.67 O 2 , respectively dispersing into distilled water, (2) Dispersing the dispersed solution into aqueous solution of citric acid, stirring in a microwave reactor, heating at 100-110 ℃ until the solvent is completely evaporated to form green gel, grinding the gel into powder, presintering at 500-510 ℃, taking out, uniformly grinding again, and roasting at 950-1000 ℃ to obtain a roasting product; (3) Dissolving C 4 H 6 MgO 4 ·4H 2 O into absolute ethyl alcohol, dispersing a roasting product into absolute ethyl alcohol to form a suspension, adding a C 4 H 6 MgO 4 ·4H 2 O solution into the roasting product suspension, stirring at 80-90 ℃ until the solvent is completely evaporated, and roasting the powder at 550-600 ℃ to obtain a product Na 0.67 Ni 0.33-x Cu x Mn 0.67 O 2 @ yMgO.
  2. 2. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating as claimed in claim 1, wherein x=0.03-0.15, and the mass fraction y of MgO is 1-5wt%.
  3. 3. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating as claimed in claim 1 or 2, wherein x is 0.05 and y is 3wt%.
  4. 4. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating, as claimed in claim 3, is characterized in that the molar ratio of citric acid to transition metal ions is 1:1.
  5. 5. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating, which is disclosed in claim 4, is characterized in that in the step (2), presintering is carried out for 5-6 hours.
  6. 6. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating as claimed in claim 5, wherein in the step (2), the roasting time is 10-12 hours, and the heating rate is set to be 3 ℃ per minute.
  7. 7. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating, which is disclosed in claim 6, is characterized in that in the step (3), roasting is carried out for 5-6 hours.
  8. 8. A P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating prepared by the preparation method of a P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating as claimed in any one of claims 1 to 7.

Description

P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating and preparation method thereof Technical Field The invention relates to the technical field of sodium ion positive electrode materials, in particular to a P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating and a preparation method thereof. Background Sodium Ion Batteries (SIBs) have received considerable attention in recent years as a low cost alternative system to lithium ion batteries due to the abundance of sodium resources and their low cost. However, the positive electrode material remains a key limiting factor in the realization of high energy density and long cycle life. The P2 type layered oxide (general formula Na xTMO2) is a research hot spot due to its larger interlayer spacing and excellent rate performance, wherein Na 0.67Ni0.33Mn0.67O2 is considered as a positive electrode candidate material with practical potential due to its higher specific capacity and lower cost, but the phase transition of P2-O 2 and the accompanying Na layer sliding and severe volume change easily occur during the high voltage charge and discharge process, so that the cycle attenuation, microcrack generation and electrolyte side reaction are aggravated. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating and a preparation method thereof. The double modification strategy of combining partial substitution of crystal lattice with magnesium oxide (MgO) surface coating is carried out by copper ions (Cu 2+) so as to improve the structural stability, interface stability and dynamic performance of the material under the high-voltage condition. The preparation method of the P2 type layered sodium ion positive electrode material based on Cu doping and MgO surface coating is characterized by comprising the following steps of: (1) Weighing CH3COONa、 NiC4H6O4·4H2O、MnC4H6O4·4H2O、C4H6CuO4·H2O, according to the stoichiometric amount of Na 0.67Ni0.33-xCuxMn0.67O2, respectively dispersing into distilled water, (2) Dispersing the dispersed solution into aqueous solution of citric acid, stirring in a microwave reactor, heating at 100-110 ℃ until the solvent is completely evaporated to form green gel, grinding the gel into powder, presintering at 500-510 ℃, taking out, uniformly grinding again, and roasting at 950-1000 ℃ to obtain a roasting product; (3) Dissolving C 4H6MgO4·4H2 O into absolute ethyl alcohol, dispersing a roasting product into absolute ethyl alcohol to form a suspension, adding a C 4H6MgO4·4H2 O solution into the roasting product suspension, stirring at 80-90 ℃ until the solvent is completely evaporated, and roasting the powder at 550-600 ℃ to obtain a product Na 0.67Ni0.33-xCuxMn0.67O2 @ yMgO. In the scheme, x=0.03-0.15, and the mass fraction y of MgO is 1-5wt%. Preferably, x is 0.05 and y is 3 wt%. In the scheme, the molar ratio of the citric acid to the transition metal ions (Ni, mn and Cu) is 1:1. In the scheme, in the step (2), presintering is carried out for 5-6 hours. In the scheme, in the step (2), the roasting time is 10-12 hours, and the heating rate is set to be 3 ℃ per minute. In the scheme, in the step (3), roasting is carried out for 5-6 hours. The P2 type lamellar sodium ion positive electrode material based on Cu doping and MgO surface coating is prepared by the preparation method of the P2 type lamellar sodium ion positive electrode material based on Cu doping and MgO surface coating. In the invention, cu 2+ is partially used for replacing Ni 2+ (forming Na 0.67Ni0.33-xCuxMn0.67O2) in the Na 0.67Ni0.33Mn0.67O2 matrix, and a thin MgO coating layer is formed on the surface of the Ni 2+ in situ. The double modification (hereinafter referred to as 'Cu-MgO double modification' or 'body-boundary double strategy') can inhibit the phase change of high-voltage P2-O 2 and obviously reduce the interface side reaction, has lower average particle diameter, shows higher discharge capacity, excellent rate capability and good cycle stability on electrochemical performance, and is a potential sodium ion layered nickel-manganese-based positive electrode material. Drawings FIG. 1 is a schematic diagram of a sample synthesis process of Na 0.67Ni0.33-xCuxMn0.67O2 @ yMgO. Fig. 2 is an XRD pattern of NM and Na 0.67Ni0.33-xCuxMn0.67O2 (x= 0.03,0.05,0.1,0.15). Fig. 3 shows (a) the cycle performance at 1C and (b) the rate performance of Na 0.67Ni0.33-xCuxMn0.67O2 (x= 0.03,0.05,0.1,0.15). FIG. 4 shows X-ray diffraction patterns of samples NM, NCM, NCM@1MgO, NCM@2MgO, NCM@3MgO and NCM@5MgO, and the right image shows the shift of the XRD main peak. FIG. 5 is an XRD refinement of samples (a) NM, (b) NCM, (c) NCM@1MgO, (d) NCM@2MgO, (e) NCM@3MgO, and (f) NCM@5MgO. FIG. 6 is an SEM image of samples (a) NM, (b) NCM, (c) NCM@1MgO, (d) NCM@2MgO, (e) NCM@3MgO,