In-situ coated copper-containing compound copper-based oxide material, preparation method and application

Abstract

The embodiment of the present invention relates to a copper-based oxide material in situ coated with a copper-containing compound, a preparation method and an application. The chemical formula of the copper-based oxide material in situ coated with a copper-containing compound is ηX α Cu β O γ ‑Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h ; X is a Na-doping element, Me is a transition metal-doping element, and Y is an O-doping element; X α Cu β O γ In the process of sintering to prepare copper-based oxide materials, Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h The copper-containing compound coating layer is generated in situ on the surface, where η is the excess molar ratio of the element X in the precursor material; during the sintering process to prepare the copper-based oxide material, the Jan-Taylor distortion is generated, which causes the production of MnO6 in the bulk phase of the material to reduce the solid solubility of the CuO6 octahedron, resulting in the precipitation of part of the Cu element from the bulk phase and enrichment on the surface, and in situ forms the copper-containing compound X together with the excess added doping element X. α Cu β O γ Coating layer; the coating layer has a channel for sodium ion diffusion in its structure, which can reduce the interface impedance and improve the cycle life of the material.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery materials, and in particular to a copper-based oxide material in situ coated with a copper-containing compound, a preparation method and an application thereof. Background Art

[0002] Lithium-ion batteries are one of the most rechargeable and dischargeable battery technologies currently available, offering the best overall performance. They are widely used in mobile electronics, electric vehicles, and the energy internet. However, as their application scale continues to expand, the limited lithium reserves in the Earth's crust are no longer sufficient to meet the growing demand.

[0003] Sodium-ion batteries have a similar working principle to lithium-ion batteries. In recent years, related research and commercial exploration have accelerated, and application demonstrations have been completed in low-speed electric vehicles, energy storage power stations, etc. However, sodium-ion batteries still have a series of technical difficulties that need to be overcome.

[0004] The cathode material of sodium-ion batteries is a key factor affecting the battery's energy density, cycle life, and rate performance. Improving cycle life can significantly reduce battery costs, thereby enhancing the market competitiveness of sodium-ion batteries.

[0005] To improve the cycle performance of sodium-ion battery positive electrode materials, improvements are usually made in the following aspects: first, improving the structural stability of the material through doping substitution; second, improving the stability of the interface between the material and the electrolyte by coating with stable compounds; third, adding suitable additives to the electrolyte to improve the stability of the interface layer.

[0006] With the material system and electrolyte system basically determined, the selection of coating materials and methods is crucial. Currently, no matter which coating method is used, such as solid-phase method, liquid-phase method, or vapor-phase method, there are limitations. In addition, no matter which method is used, additional coating treatment is required after the positive electrode material is prepared. This greatly increases the material preparation cycle, difficulty and processing cost. Summary of the Invention

[0007] The purpose of the present invention is to provide a copper-based oxide material in situ coated with a copper-containing compound, a preparation method and an application thereof, which utilizes the Jan-Taylor distortion in the material preparation and synthesis process, and realizes the one-step in situ coating of the copper-based oxide material by adding an excess of X element to form a copper-containing compound X. α Cu β O γ The structure of the coating layer has a channel for sodium ion diffusion, which can reduce the interface impedance and improve the cycle life of the material.

[0008] To this end, in a first aspect, an embodiment of the present invention provides a copper-based oxide material in situ coated with a copper compound, wherein the chemical formula of the copper-based oxide material in situ coated with a copper compound is:

[0009] ηX α Cu β O γ -Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h ;

[0010] X is a Na-site doping element, including one or more of Li, Mg, K, Ca, and Al; Me is a transition metal-site doping element, including one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; Y is an O-site doping element, including one or more of F, N, S, Cl, Br, and Se; a, b, c, d, e, f, 2+g, and h represent Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h the number of corresponding atoms in the molecule;

[0011] X α Cu β O γ In the process of sintering to prepare copper-based oxide materials, Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h The copper compound coating layer is generated in situ on the surface, and η is the molar ratio of the excess element X in the precursor material; wherein 0.1%≤η≤8%, 1≤α≤2, 1≤β≤2, and 2≤γ≤4;

[0012] During the sintering process of preparing copper-based oxide materials, the Jan-Taylor distortion occurs, which causes the production of MnO6 in the bulk phase of the material to reduce the solid solubility of CuO6 octahedron, resulting in the precipitation of some Cu elements from the bulk phase and enrichment on the surface, and in situ forming a copper-containing compound X together with the excessively added doping element X. α Cu β O γ The coating layer has a sodium ion diffusion channel in its structure.

[0013] Preferably, the average valence of X is +B, 1≤B≤3; the valence of Cu is +C, 1≤C≤3; the valence of Fe is +D, 2≤D≤4; the valence of Mn is +E, 2≤D≤5; the average valence of Me is +F, 1≤F≤6; the average valence of Y is -H, 1≤H≤3;

[0014] The relationship between a, b, c, d, e, f, g, and h satisfies c+d+e+f=1, and a+B×b+C×c+D×d+F×f=2×(2+g)+H×h; where 0.5≤a≤2.0; 0<b≤0.1; 0<c<1.0; 0≤d<1.0; 0<e<1.0; 0≤f<1.0; -0.1≤g≤0.1; 0≤h≤0.1.

[0015] In a second aspect, an embodiment of the present invention provides a method for preparing the copper-based oxide material in situ coated with a copper compound as described in the first aspect above, wherein the method is a solid phase method, comprising:

[0016] The sodium carbonate of 100 wt% to 108 wt% of the required sodium stoichiometric amount and the Cu2O and / or CuO, Fe2O3 and / or Fe3O4, MnO2, MeO x , an oxide or salt containing an element Y, and an oxide or salt containing an element X in an amount of 100.1 wt% to 108 wt% of the stoichiometric amount of the required X are mixed in proportion to form a precursor; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al;

[0017] The precursors are uniformly mixed by ball milling to obtain precursor powder;

[0018] The precursor powder is placed in a muffle furnace and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0019] The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

[0020] In a third aspect, an embodiment of the present invention provides a method for preparing the copper-based oxide material in situ coated with a copper compound as described in the first aspect, wherein the method is a spray drying method, comprising:

[0021] The sodium carbonate of 100 wt% to 108 wt% of the required sodium stoichiometric amount and the Cu2O and / or CuO, Fe2O3 and / or Fe3O4, MnO2, MeO x , an oxide or salt containing an element Y, and an oxide or salt containing an element X in an amount of 100.1 wt% to 108 wt% of the stoichiometric amount of the required X are mixed in proportion to form a precursor; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al;

[0022] Adding ethanol or water to the precursor and stirring evenly to form a slurry;

[0023] spray drying the slurry to obtain a precursor powder;

[0024] The precursor powder is placed in a muffle furnace and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0025] The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

[0026] In a fourth aspect, an embodiment of the present invention provides a method for preparing the copper-based oxide material in situ coated with a copper compound as described in the first aspect, wherein the method is a spray drying method, comprising:

[0027] Sodium acetate, sodium nitrate, sodium carbonate, or sodium sulfate containing 100 wt% to 108 wt% of the required sodium stoichiometry, nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, respectively, and nitrates or sulfates containing the required X element containing 100.1 wt% to 108 wt% of the required X stoichiometric amount are dissolved in water or ethanol in proportion to form a precursor solution; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al;

[0028] Adding ethanol or water to the precursor solution and stirring uniformly to form a slurry;

[0029] spray drying the slurry to obtain a precursor powder;

[0030] The precursor powder is placed in a muffle furnace and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0031] The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

[0032] In a fifth aspect, an embodiment of the present invention provides a method for preparing the copper-based oxide material in situ coated with a copper compound as described in the first aspect above, wherein the method is a sol-gel method, comprising:

[0033] Sodium acetate, sodium nitrate, sodium carbonate, or sodium sulfate containing 100 wt% to 108 wt% of the required sodium stoichiometry, nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, respectively, and nitrates or sulfates containing the required X element containing 100.1 wt% to 108 wt% of the required X stoichiometry are dissolved in water or ethanol in proportion to form a precursor solution; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al;

[0034] The precursor solution is stirred at 50° C. to 100° C., and a chelating agent is added in an amount 2-6 times the total molar amount of the transition metal, and evaporated to dryness to form a precursor gel; the transition metal includes Cu, Fe, Mn, and Me;

[0035] The precursor gel is placed in a crucible and pre-fired in an air atmosphere at 200° C. to 500° C. for 2 hours;

[0036] Then heat treat at 600℃~1000℃ for 2~24 hours;

[0037] The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

[0038] In a sixth aspect, an embodiment of the present invention provides a method for preparing the copper-based oxide material in situ coated with a copper compound as described in the first aspect above, wherein the method is a co-precipitation method, comprising:

[0039] Dissolving nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, and nitrates or sulfates containing the required X element in an amount of 100.1 wt% to 108 wt% in water or ethanol to form solutions, respectively; wherein Me comprises one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; Y comprises one or more of F, N, S, Cl, Br, and Se; and X comprises one or more of Li, Mg, K, Ca, and Al;

[0040] Use a peristaltic pump to drop each solution sequentially into an ammonia solution with a pH value between 7 and 14 to generate a precipitate;

[0041] The obtained precipitate is washed with deionized water, dried, and then uniformly mixed with sodium carbonate having a stoichiometric amount of 100 wt% to 108 wt% of the required sodium to obtain a precursor;

[0042] The precursor is placed in a crucible and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0043] The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

[0044] In the seventh aspect, an embodiment of the present invention provides a positive electrode plate for a sodium ion secondary battery, comprising a current collector, a conductive additive coated on the current collector, a binder, and the copper-based oxide material in situ coated with a copper compound as described in the first aspect above.

[0045] In an eighth aspect, an embodiment of the present invention provides a sodium ion secondary battery comprising the positive electrode sheet described in the seventh aspect.

[0046] In a ninth aspect, an embodiment of the present invention provides a use of the sodium ion secondary battery described in the eighth aspect above, wherein the sodium ion secondary battery is used for large-scale energy storage equipment for solar power generation, wind power generation, smart grid peak regulation, distributed power stations, backup power supplies or communication base stations.

[0047] The embodiment of the present invention provides a copper-based oxide material coated with a copper-containing compound in situ, which utilizes the Jan-Taylor distortion in the material preparation and synthesis process, so that the solid solubility of CuO6 octahedron is reduced by the generation of MnO6 in the bulk phase of the material. In addition, by adding an excessive amount of X element, part of the Cu element is precipitated from the bulk phase and enriched on the surface, and in situ forms a copper-containing compound X together with the excessively added doping element X. α Cu β O γ The coating layer achieves a one-step, in-situ, uniform coating of the copper-based oxide material, saving preparation steps and shortening process time. The resulting coating layer has channels for sodium ion diffusion, which has higher ionic and electronic conductivity than the traditional CuO coating layer alone, reduces interfacial impedance, and effectively improves the stability of the surface crystal structure of the positive electrode material and reduces side reactions between the positive electrode and the electrolyte, thereby effectively extending the cycle life of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of material structure changes during the sintering process of preparing a copper-based oxide material according to an embodiment of the present invention;

[0049] Figure 2 X-ray diffraction (XRD) patterns of multiple oxide materials with different molar percentages of elements provided by embodiments of the present invention;

[0050] Figure 3 This is a charge and discharge curve diagram of the sodium ion battery provided in Example 1 of the present invention at 2.5-3.95V;

[0051] Figure 4 This is a charge and discharge curve diagram of the sodium ion battery provided in Example 2 of the present invention at 2.5-3.95V;

[0052] Figure 5This is a charge and discharge curve diagram of the sodium ion battery provided in Example 3 of the present invention at 2.5-4.0V;

[0053] Figure 6 This is a graph showing the capacity retention rate of the sodium ion battery provided in Example 3 of the present invention at 2.5-4.0V cycle. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0055] The embodiment of the present invention provides a copper-based oxide material in situ coated with a copper-containing compound, the chemical formula of which is: ηX α Cu β O γ -Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h ;

[0056] Wherein, X is a Na-site doping element, including one or more of Li, Mg, K, Ca, and Al; Me is a transition metal-site doping element, including one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; Y is an O-site doping element, including one or more of F, N, S, Cl, Br, and Se;

[0057] The average valence of X is +B, 1≤B≤3; the valence of Cu is +C, 1≤C≤3; the valence of Fe is +D, 2≤D≤4; the valence of Mn is +E, 2≤D≤5; the average valence of Me is +F, 1≤F≤6; the average valence of Y is -H, 1≤H≤3;

[0058] a, b, c, d, e, f, 2+g, h represent Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y hThe number of corresponding atoms in the molecule; the relationship between a, b, c, d, e, f, g, and h satisfies c+d+e+f=1, and a+B×b+C×c+D×d+F×f=2×(2+g)+H×h; among which 0.5≤a≤2.0; 0<b≤0.1; 0<c<1.0; 0≤d<1.0; 0<e<1.0; 0≤f<1.0; -0.1≤g≤0.1; 0≤h≤0.1.

[0059] X α Cu β O γ In the process of sintering to prepare copper-based oxide materials, Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h The copper compound coating layer is generated in situ on the surface, and η is the molar ratio of the excess element X in the precursor material; wherein 0.1%≤η≤8%, 1≤α≤2, 1≤β≤2, and 2≤γ≤4;

[0060] During the sintering process of preparing copper-based oxide materials, the oxide materials lose oxygen at high temperatures, resulting in the production of MnO6 with Jiang Taylor distortion. The production of MnO6 reduces the solid solubility of CuO6 octahedrons with Jiang Taylor distortion, causing a small amount of Cu element to precipitate from the bulk phase of the oxide material positive electrode particles and accumulate on the surface of the positive electrode particles, and in situ form a copper-containing compound X together with the excessively added doping element X. α Cu β O γ Coating layer, process diagram as shown Figure 1 As shown in the figure, the coating layer neither reduces the number of active sodium ions in the bulk phase nor causes capacity loss. Moreover, since the coating layer has a sodium ion diffusion channel in its structure, it has higher ionic conductivity and electronic conductivity than a simple CuO coating layer, reduces interfacial impedance, and can effectively improve the stability of the surface crystal structure of the positive electrode material and reduce the side reactions between the positive electrode and the electrolyte, thereby effectively improving the cycle life of the positive electrode material.

[0061] The copper-based oxide material in situ coated with a copper compound of the present invention can be used in a positive electrode sheet. The material is prepared by mixing the copper-based oxide material in situ coated with a copper compound with a conductive additive and a binder, and then coating the mixture on a current collector. The conductive additive, binder, and current collector used can all be those commonly used in sodium ion battery positive electrodes in the prior art and are not particularly limited herein.

[0062] The sodium ion secondary battery loaded with the above-mentioned positive electrode plate can be used in large-scale energy storage equipment for solar power generation, wind power generation, smart grid peak regulation, distributed power stations, backup power supplies or communication base stations.

[0063] The copper-based oxide material in situ coated with a copper compound of the present invention can be prepared by the following methods.

[0064] In the first method, a solid phase method is used for preparation, and the main steps include:

[0065] S1, sodium carbonate of 100wt% to 108wt% of the required sodium stoichiometric amount and Cu2O and / or CuO, Fe2O3 and / or Fe3O4, MnO2, MeO x , an oxide or salt containing element Y, and an oxide or salt containing element X in an amount of 100.1 wt% to 108 wt% of the desired stoichiometric amount of X are mixed in proportion to form a precursor;

[0066] Wherein, Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; X includes one or more of Li, Mg, K, Ca, and Al;

[0067] S2, uniformly mixing the precursors by ball milling to obtain precursor powder;

[0068] S3, placing the precursor powder in a muffle furnace and heat treating it in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0069] S4, grinding the heat-treated material to obtain a copper-based oxide material in situ coated with a copper compound.

[0070] In the second method, spray drying is used for preparation, and the main steps include:

[0071] S1, sodium carbonate of 100wt% to 108wt% of the required sodium stoichiometric amount and Cu2O and / or CuO, Fe2O3 and / or Fe3O4, MnO2, MeO x , an oxide or salt containing element Y, and an oxide or salt containing element X in an amount of 100.1 wt% to 108 wt% of the desired stoichiometric amount of X are mixed in proportion to form a precursor;

[0072] Wherein, Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; X includes one or more of Li, Mg, K, Ca, and Al;

[0073] S2, adding ethanol or water to the precursor and stirring evenly to form a slurry;

[0074] S3, spray drying the slurry to obtain a precursor powder;

[0075] S4, placing the precursor powder in a muffle furnace and heat treating it in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0076] S5, grinding the heat-treated material to obtain a copper-based oxide material in situ coated with a copper compound.

[0077] In the third method, another spray drying method is used for preparation, and the main steps include:

[0078] S1, dissolving sodium acetate or sodium nitrate or sodium carbonate or sodium sulfate containing 100 wt% to 108 wt% of the stoichiometric amount of the required sodium, nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, respectively, and nitrates or sulfates containing the required stoichiometric amount of X element at 100.1 wt% to 108 wt% in proportion in water or ethanol to form a precursor solution;

[0079] Wherein, Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; X includes one or more of Li, Mg, K, Ca, and Al;

[0080] S2, adding ethanol or water to the precursor solution and stirring uniformly to form a slurry;

[0081] S3, spray drying the slurry to obtain a precursor powder;

[0082] S4, placing the precursor powder in a muffle furnace and heat treating it in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0083] S5, grinding the heat-treated material to obtain a copper-based oxide material in situ coated with a copper compound.

[0084] In the fourth method, the sol-gel method is used for preparation, and the main steps include:

[0085] S1, dissolving sodium acetate or sodium nitrate or sodium carbonate or sodium sulfate containing 100 wt% to 108 wt% of the required sodium stoichiometry, nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, respectively, and nitrates or sulfates containing the required X stoichiometric amount of 100.1 wt% to 108 wt% in water or ethanol in proportion to form a precursor solution;

[0086] Wherein, Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; X includes one or more of Li, Mg, K, Ca, and Al;

[0087] S2, stirring the precursor solution at 50° C. to 100° C., adding citric acid as a chelating agent in an amount 2-6 times the total molar amount of the transition metal, and evaporating to dryness to form a precursor gel; the transition metal includes Cu, Fe, Mn, and Me in the above steps.

[0088] S3, placing the precursor gel in a crucible and pre-calcining it in an air atmosphere at 200°C to 500°C for 2 hours;

[0089] S4, further heat treating at 600°C to 1000°C for 2 to 24 hours;

[0090] S5, grinding the heat-treated material to obtain a copper-based oxide material in situ coated with a copper compound.

[0091] In the fifth method, a coprecipitation method is used for preparation, and the main steps include:

[0092] S1, dissolving nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, and nitrates or sulfates containing the required stoichiometric amount of X element at 100.1 wt% to 108 wt% in water or ethanol to form solutions;

[0093] Wherein, Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; Y includes one or more of F, N, S, Cl, Br, and Se; X includes one or more of Li, Mg, K, Ca, and Al;

[0094] S2, using a peristaltic pump, sequentially adding each solution dropwise to an ammonia solution having a pH value between 7 and 14 to generate a precipitate;

[0095] S3, washing the obtained precipitate with deionized water, drying it, and then uniformly mixing it with sodium carbonate having a stoichiometric amount of 100 wt% to 108 wt% of the required sodium to obtain a precursor;

[0096] S4, placing the precursor in a crucible and heat treating it in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours;

[0097] S5, grinding the heat-treated material to obtain a copper-based oxide material in situ coated with a copper compound.

[0098] To better understand the technical solutions provided by the present invention, the following uses a number of specific examples to illustrate the specific process of preparing the in-situ coated copper-containing compound copper-based oxide material using the several methods provided in the above embodiments of the present invention, as well as the method and battery characteristics of applying it to sodium ion secondary batteries.

[0099] Example 1

[0100] In this embodiment, a solid phase method is used to prepare a copper-based oxide material in situ coated with a copper compound.

[0101] Na2CO3 (analytical grade) with a stoichiometric amount of 108 wt% of the required sodium, K2CO3 (analytical grade) with a stoichiometric amount of 100.5 wt% of the required K, and CuO (analytical grade), Fe2O3 (analytical grade), and MnO2 (analytical grade) with a stoichiometric amount are mixed in proportion and ground in an agate mortar for half an hour to obtain a precursor powder;

[0102] The precursor powder was pressed into a tablet and transferred to an Al2O3 crucible. It was treated at 900℃ for 15 hours in an air atmosphere in a muffle furnace to obtain a black powder oxide material, which was an in-situ coated copper-containing compound copper-based oxide material 0.5% K2CuO2-Na 5 / 6 K 1 / 12 Cu 3.5 / 12 Fe 4 / 12 Mn 4.5 / 12 O2.

[0103] The X-ray diffraction pattern of the obtained material can be found in Figure 2 From the X-ray diffraction pattern, 0.5% K2CuO2-Na 5 / 6K 1 / 12 Cu 3.5 / 12 Fe 4 / 12 Mn 4.5 / 12 The crystal structure of O2 is an oxide with an O3 phase layered structure.

[0104] The copper-based oxide material prepared in situ coated with a copper compound is used as the active material of the battery positive electrode material for the preparation of a sodium ion battery:

[0105] Prepared 0.5% K2CuO2-Na 5 / 6 K 1 / 12 Cu 3.5 / 12 Fe 4 / 12 Mn 4.5 / 12 O2 powder, acetylene black and binder polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 80:10:10, and an appropriate amount of N-methylpyrrolidone (NMP) solution was added. The mixture was ground in a dry environment at room temperature to form a slurry. The slurry was then evenly coated on the current collector aluminum foil and dried under an infrared lamp before being cut into (8×8) mm 2 The electrode was dried at 110°C under vacuum for 10 hours and then transferred to a glove box for later use.

[0106] The simulated battery was assembled in an Ar atmosphere glove box, using sodium metal as the counter electrode and a NaClO4 / (ethylene carbonate (EC):propylene carbonate (PC), 1:1 volume ratio) solution as the electrolyte, to form a CR2032 button cell. Charge and discharge tests were conducted using a constant current charge and discharge mode at a current density of 10mA / g. Under conditions of a discharge cut-off voltage of 2.5V and a charge cut-off voltage of 3.95V, the first-week discharge capacity reached 113.1mAh / g. The test results are shown in the table below. Figure 3 .

[0107] Example 2

[0108] In this embodiment, the first spray drying method is used to prepare the copper-based oxide material in situ coated with a copper compound.

[0109] The required sodium stoichiometric 108wt% Na2CO3 (analytical grade), the required K stoichiometric 101.3wt% K2CO3 (analytical grade), and the required stoichiometric CuO (analytical grade), Fe2O3 (analytical grade), and MnO2 (analytical grade) were mixed in proportion, and ethanol was added and stirred to form a slurry; the obtained slurry was spray-dried to obtain a precursor powder; the precursor powder was placed in a muffle furnace and heat-treated under the conditions of air atmosphere, 900°C, and 15 hours to obtain a black powder oxide material, which is a copper-based oxide material in situ coated with a copper compound containing 1.3% K2CuO2-Na 8 / 9 K 1 / 24 Cu 2.5 / 9 Fe 3.5 / 9 Mn 3.5 / 9 O2.

[0110] The X-ray diffraction pattern of the obtained material can be found in Figure 1 From the X-ray diffraction pattern, 1.3% K2CuO2-Na 8 / 9K 1 / 24 Cu 2.5 / 9 Fe 3.5 / 9 Mn 3.5 / 9 The crystal structure of O2 is an oxide with an O3 phase layered structure.

[0111] Example 3

[0112] In this embodiment, a solid phase method is used to prepare a copper-based oxide material in situ coated with a copper compound.

[0113] The specific preparation steps were the same as in Example 6, except that the precursor compounds used were Na2CO3 (analytical grade), Li2CO3 (analytical grade), CuO (analytical grade), Fe2O3 (analytical grade), and MnO2 (analytical grade), and the stoichiometric ratios were different from those in Example 1. The amount of Li2CO3 (analytical grade) was 100.7 wt% of the stoichiometric amount of the required Li. The amount of Na2CO3 (analytical grade) was 105 wt% of the stoichiometric amount of the required copper.

[0114] The oxide material of black powder obtained after heat treatment is a copper-based oxide material 0.7% Li2CuO2-Na2O3 coated with a copper compound in situ. 7 / 9 Li 1 / 9 Cu 2 / 9 Fe 4 / 9 Mn 3 / 9 O2.

[0115] The X-ray diffraction pattern of the obtained material can be found in Figure 1 From the X-ray diffraction pattern, 0.7% Li2CuO2-Na 7 / 9Li 1 / 9 Cu2 / 9 Fe 4 / 9 Mn 3 / 9 The crystal structure of O2 is an oxide with an O3 phase layered structure.

[0116] The copper-based oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of sodium ion batteries, and electrochemical charge and discharge tests were carried out. The preparation process and test method were the same as in Example 1. Under the conditions of discharge cut-off voltage of 2.5V and charge cut-off voltage of 3.95V, the first-week discharge capacity can reach 112.1mAh / g. The test results are shown in FIG. Figure 4 .

[0117] Example 4

[0118] In this embodiment, a co-precipitation method is used to prepare a copper-based oxide material in situ coated with a copper-containing compound.

[0119] CuSO4, FeSO4, and MnSO4 are dissolved in water according to a stoichiometric ratio to form solutions, and the resulting solutions are slowly added dropwise to an ammonia solution with a pH of 12 using a peristaltic pump to generate a precipitate. The resulting precipitate is cleaned with deionized water, dried, and then uniformly mixed with sodium carbonate and calcium carbonate with a total sodium content of 108 wt% of the stoichiometric amount of the required sodium and sodium fluoride with a stoichiometric amount of 104.2 wt% of the stoichiometric amount of the required Li to obtain a precursor. The precursor is placed in a crucible and heat treated under air atmosphere, 900°C, and 15 hours to obtain a black powder oxide material, which is a copper-based oxide material in situ coated with a copper compound containing 4.2% CaCuO2-Na 5 / 9 Ca 1 / 9 Cu 2 / 9 Fe 3 / 9 Mn 4 / 9 O2F 1 / 24 ;

[0120] The X-ray diffraction pattern of the obtained material can be found in Figure 1 From the X-ray diffraction pattern, 4.2% CaCuO2-Na 5 / 9 Ca 1 / 9 Cu 2 / 9 Fe 3 / 9 Mn 4 / 9 O2F 1 / 24 The crystal structure is an oxide with an O3 phase layered structure.

[0121] Example 5

[0122] In this embodiment, a solid phase method is used to prepare a copper-based oxide material in situ coated with a copper compound.

[0123] The specific preparation steps were the same as in Example 1, except that the precursor compounds used were Na2CO3 (analytical grade), Li2CO3 (analytical grade), CuO (analytical grade), and MnO2 (analytical grade), and the stoichiometric ratios were different from those in Example 1. The amount of Li2CO3 (analytical grade) was 103.6 wt% of the stoichiometric amount of the required Li. The amount of Na2CO3 (analytical grade) was 105 wt% of the stoichiometric amount of the required copper.

[0124] The oxide material of black powder obtained after heat treatment is a copper-based oxide material 3.6% Li2CuO2-Na2O3 coated with a copper compound in situ. 0.6 Li 0.06 Cu 0.34 Mn 0.66 O2.

[0125] The X-ray diffraction pattern of the obtained material can be found in Figure 1 From the X-ray diffraction pattern, 3.6% Li2CuO2-Na 0.6 Li 0.06 Cu 0.34 Mn 0.66 The crystal structure of O2 is a P2 phase layered oxide.

[0126] The copper-based oxide material prepared above was used as the active material of the battery positive electrode material for the preparation of sodium ion batteries, and electrochemical charge and discharge tests were carried out. The preparation process and test method were the same as in Example 1. Under the conditions of a discharge cut-off voltage of 2.5V and a charge cut-off voltage of 4.0V, the first-week discharge capacity can reach 79.2mAh / g. The test results are shown in FIG. Figure 5 .

[0127] For comparison, the applicant followed the method of Example 5, changed the amount of Na2CO3 (analytical grade) to 100 wt% of the stoichiometric amount of the required sodium, changed the amount of Li2CO3 (analytical grade) to 100 wt% of the stoichiometric amount of the required lithium, and adjusted the stoichiometric ratio between the precursor compounds to synthesize Na2CO3 without in-situ coating of the copper-containing compound. 0.6 Li 0.06 Cu 0.34 Mn 0.66 O2, heat treatment conditions are air atmosphere, 800℃, 15 hours.

[0128] 3.6%Li2CuO2-Na 0.6 Li 0.06 Cu 0.34 Mn 0.66 O2 and Na 0.6 Li 0.06 Cu 0.34 Mn 0.66The comparison of O2 cycle capacity retention rate is shown in Figure 6 . Of which 3.6% Li2CuO2-Na 0.6 Li 0.06 Cu 0.34 Mn 0.66 The capacity retention rate of O2 after 200 cycles was 75.25%, which was much higher than that of Na2O2 without in-situ coating of copper compounds. 0.6 Li 0.06 Cu 0.34 Mn 0.66 58.49% of O2.

[0129] During the sintering process of preparing copper-based oxide materials, the oxide materials lose oxygen at high temperatures, resulting in the production of MnO6 with Jan-Taylor distortion. The production of MnO6 reduces the solid solubility of CuO6 octahedrons with the same Jan-Taylor distortion, causing a small amount of Cu element to precipitate from the bulk of the oxide material and accumulate on the surface of the material, and together with the excessively added doping element X, form a copper-containing compound X in situ. α Cu β O γ Coating layer; the coating layer neither reduces the number of active sodium ions in the bulk phase nor causes capacity loss, and because the coating layer has a sodium ion diffusion channel in its structure, it has higher ionic conductivity and electronic conductivity than a simple CuO coating layer, reduces interfacial impedance, and can effectively improve the stability of the surface crystal structure of the positive electrode material and reduce side reactions between the positive electrode and the electrolyte, thereby effectively improving the cycle life of the positive electrode material.

[0130] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A copper-based oxide material in situ coated with a copper compound, characterized in that: The chemical formula of the copper-based oxide material in situ coated with a copper compound is: ηX α Cu β O γ -Na a X b [Cu c Feb d Mr e Along with f ]O 2+g Y h ; X is a Na-site doping element, including one or more of Li, Mg, K, Ca, and Al; Me is a transition metal-site doping element, including one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; Y is an O-site doping element, including one or more of F, N, S, Cl, Br, and Se; a, b, c, d, e, f, 2+g, and h represent Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h the number of corresponding atoms in the molecule; X α Cu β O γ In the process of sintering to prepare copper-based oxide materials, Na a X b [Cu c Fe d Mn e Me f ]O 2+g Y h The copper compound coating layer is generated in situ on the surface, and η is the molar ratio of the excess element X in the precursor material; wherein 0.1%≤η≤8%, 1≤α≤2, 1≤β≤2, and 2≤γ≤4; During the sintering process of preparing copper-based oxide materials, the Jan-Taylor distortion occurs, which causes the production of MnO6 in the bulk phase of the material to reduce the solid solubility of CuO6 octahedron, resulting in the precipitation of some Cu elements from the bulk phase and enrichment on the surface, and in situ forming a copper-containing compound X together with the excessively added doping element X. α Cu β O γ The coating layer has a sodium ion diffusion channel in its structure.

2. The copper-based oxide material according to claim 1, characterized in that The average valence of X is +B, 1≤B≤3; the valence of Cu is +C, 1≤C≤3; the valence of Fe is +D, 2≤D≤4; the valence of Mn is +E, 2≤D≤5; the average valence of Me is +F, 1≤F≤6; the average valence of Y is -H, 1≤H≤3; The relationship between a, b, c, d, e, f, g, and h satisfies c + d + e + f = 1, and a + B × b + C × c + D × d + F × f = 2 × (2 + g) + H × h; where 0.5 ≤ a ≤ 2.0; 0 < b ≤ 0.1; 0<c<1.0; 0≤d<1.0; 0<e<1.0; 0≤f<1.0; -0.1≤g≤0.1; 0≤h≤0.

1.

3. A method for preparing a copper-based oxide material in situ coated with a copper compound according to claim 1 or 2, characterized in that: The method is a solid phase method, comprising: The sodium carbonate of 100 wt% to 108 wt% of the required sodium stoichiometric amount and the Cu2O and / or CuO, Fe2O3 and / or Fe3O4, MnO2, MeO x , an oxide or salt containing an element Y, and an oxide or salt containing an element X in an amount of 100.1 wt% to 108 wt% of the stoichiometric amount of the required X are mixed in proportion to form a precursor; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al; The precursors are uniformly mixed by ball milling to obtain precursor powder; The precursor powder is placed in a muffle furnace and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours; The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

4. A method for preparing a copper-based oxide material in situ coated with a copper compound according to claim 1 or 2, characterized in that: The method is a spray drying method, comprising: The sodium carbonate of 100 wt% to 108 wt% of the required sodium stoichiometric amount and the Cu2O and / or CuO, Fe2O3 and / or Fe3O4, MnO2, MeO x , an oxide or salt containing an element Y, and an oxide or salt containing an element X in an amount of 100.1 wt% to 108 wt% of the stoichiometric amount of the required X are mixed in proportion to form a precursor; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al; Adding ethanol or water to the precursor and stirring evenly to form a slurry; spray drying the slurry to obtain a precursor powder; The precursor powder is placed in a muffle furnace and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours; The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

5. A method for preparing a copper-based oxide material in situ coated with a copper compound according to claim 1 or 2, characterized in that: The method is a spray drying method, comprising: Sodium acetate, sodium nitrate, sodium carbonate, or sodium sulfate containing 100 wt% to 108 wt% of the required sodium stoichiometry, nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, respectively, and nitrates or sulfates containing the required X element containing 100.1 wt% to 108 wt% of the required X stoichiometric amount are dissolved in water or ethanol in proportion to form a precursor solution; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al; Adding ethanol or water to the precursor solution and stirring uniformly to form a slurry; spray drying the slurry to obtain a precursor powder; The precursor powder is placed in a muffle furnace and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours; The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

6. A method for preparing a copper-based oxide material in situ coated with a copper compound according to claim 1 or 2, characterized in that: The method is a sol-gel method, comprising: Sodium acetate, sodium nitrate, sodium carbonate, or sodium sulfate containing 100 wt% to 108 wt% of the required sodium stoichiometry, nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, respectively, and nitrates or sulfates containing the required X element containing 100.1 wt% to 108 wt% of the required X stoichiometry are dissolved in water or ethanol in proportion to form a precursor solution; wherein Me includes one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; 0.5≤x≤3; Y includes one or more of F, N, S, Cl, Br, and Se; and X includes one or more of Li, Mg, K, Ca, and Al; The precursor solution is stirred at 50° C. to 100° C., and a chelating agent is added in an amount 2-6 times the total molar amount of the transition metal, and evaporated to dryness to form a precursor gel; the transition metal includes Cu, Fe, Mn, and Me; The precursor gel is placed in a crucible and pre-fired in an air atmosphere at 200° C. to 500° C. for 2 hours; Then heat treat at 600℃~1000℃ for 2~24 hours; The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

7. A method for preparing a copper-based oxide material in situ coated with a copper compound as claimed in claim 1 or 2, characterized in that: The method is a co-precipitation method, comprising: Dissolving nitrates or sulfates containing the required stoichiometric amounts of Cu, Fe, Mn, Me, and Y elements, and nitrates or sulfates containing the required X element in an amount of 100.1 wt% to 108 wt% in water or ethanol to form solutions, respectively; wherein Me comprises one or more of Li, B, Na, Mg, Ca, Si, P, S, Sc, Ti, V, Cr, Co, Ni, Zn, Ga, Ge, Se, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, La, Ta, Ir, and Bi; Y comprises one or more of F, N, S, Cl, Br, and Se; and X comprises one or more of Li, Mg, K, Ca, and Al; Use a peristaltic pump to drop each solution sequentially into an ammonia solution with a pH of 7-14 to generate a precipitate; The obtained precipitate is washed with deionized water, dried, and then uniformly mixed with sodium carbonate having a stoichiometric amount of 100 wt% to 108 wt% of the required sodium to obtain a precursor; The precursor is placed in a crucible and heat treated in an air atmosphere at 600° C. to 1000° C. for 2 to 24 hours; The heat-treated material is ground to obtain the copper-based oxide material coated with the copper compound in situ.

8. A positive electrode plate for a sodium ion secondary battery, characterized in that: The positive electrode plate comprises: a current collector, a conductive additive coated on the current collector, a binder, and the copper-based oxide material in situ coated with a copper compound according to claim 1 or 2.

9. A sodium ion secondary battery comprising the positive electrode sheet according to claim 8.

10. Use of the sodium ion secondary battery according to claim 9, characterized in that: The sodium ion secondary battery is used for large-scale energy storage equipment in solar power generation, wind power generation, smart grid peak regulation, distributed power stations, backup power supplies or communication base stations.

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