WO2024087568A1 - 一种锰基固溶体正极材料及制备方法与用途 - Google Patents

一种锰基固溶体正极材料及制备方法与用途 Download PDF

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WO2024087568A1
WO2024087568A1 PCT/CN2023/092144 CN2023092144W WO2024087568A1 WO 2024087568 A1 WO2024087568 A1 WO 2024087568A1 CN 2023092144 W CN2023092144 W CN 2023092144W WO 2024087568 A1 WO2024087568 A1 WO 2024087568A1
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manganese
positive electrode
solid solution
sodium
electrode material
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French (fr)
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胡骐
曾汉民
李思
周聪
徐悦斌
何巍
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湖北亿纬动力有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C01G45/12—Manganates manganites or permanganates
    • C01G45/1221—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
    • C01G45/1228—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type [MnO2]n-, e.g. LiMnO2, Li[MxMn1-x]O2
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G45/00—Compounds of manganese
    • C01G45/12—Manganates manganites or permanganates
    • C01G45/1221—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof
    • C01G45/125—Manganates or manganites with a manganese oxidation state of Mn(III), Mn(IV) or mixtures thereof of the type[MnO3]n-, e.g. Li2MnO3, Li2[MxMn1-xO3], (La,Sr)MnO3
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/40—Electric properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the embodiments of the present application relate to the technical field of lithium-ion batteries, for example, a manganese-based solid solution positive electrode material and a preparation method and use thereof.
  • the manganese-based material LiMnO2 has a theoretical capacity of 285mAh/g and great potential for capacity development. It also has the advantages of low cost, abundant raw materials, and excellent safety performance. However, its high-temperature performance is poor, and a suitable solution needs to be found to stabilize its structure and avoid spinelization.
  • CN102800840A discloses a quasi-spherical lithium manganate and its preparation method, which reduces the specific surface area of the material, thereby reducing the dissolution of manganese and improving the cycle performance of the battery.
  • this method only regulates the material morphology and cannot effectively isolate the direct contact between lithium manganate and the electrolyte.
  • the surface is coated with inorganic materials such as oxides, phosphates, and fluorides. By coating with inert materials, the direct contact between the positive electrode material and the electrolyte is isolated, the dissolution of manganese is reduced, and the cyclability of the battery is improved.
  • CN104134793A discloses a preparation method for lithium manganate, a positive electrode material for lithium ion batteries, which uses doped modified lithium manganate to coat ordinary lithium manganate to improve the cycle performance of the material.
  • doped modified lithium manganate is prone to introduce crystal defects during the production process, resulting in poor product consistency, and this modification method has an effective effect on the degree of weakening of side reactions occurring on the surface of lithium manganate.
  • CN102054985A discloses a lithium manganese oxide and a preparation method thereof.
  • the compatibility of the material with the electrolyte is improved, thereby improving the high-temperature and room-temperature cycle performance and high-temperature storage performance.
  • This method coats a compound with low crystallinity on the surface of a precursor with high crystallinity. Because the crystal structures of the two materials are different, new grain boundaries will be formed between the coating material and the core material. During the rolling process of the pole piece, the lithium manganese oxide material will rupture due to the large internal stress, resulting in poor battery cycle performance.
  • the embodiment of the present application provides a manganese-based solid solution positive electrode material and a preparation method and use.
  • the embodiment of the present application provides a manganese-based solid solution material with a layered structure.
  • the introduction of the sodium manganese-based material forms a solid solution with the manganese-based matrix material, avoiding the formation of the spinel phase of the manganese-based material, improving the stability of the layered structure, and thus improving the cycle stability of the positive electrode material.
  • the sodium manganese-based material has a high conductivity, which also improves the conductivity of the positive electrode material and improves its capacity.
  • an embodiment of the present application provides a manganese-based solid solution positive electrode material, wherein the manganese-based solid solution positive electrode material is a layered structure, and the chemical formula of the manganese-based solid solution positive electrode material is aNa2MnxR (1-x) O3 ⁇ (1-a) LiMnyM (1-y) O2 , wherein 0.05 ⁇ a ⁇ 1, 0 ⁇ x ⁇ 1, 0.1 ⁇ y ⁇ 1, and R and M in the chemical formula independently include any one or a combination of at least two of alkali metal elements, alkaline earth metal elements or transition metal elements.
  • the a can be 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 0.99, etc.;
  • the x can be 0.05, 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.
  • the y can be 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.
  • the present application provides a manganese-based solid solution material with a layered structure.
  • the introduction of a sodium-manganese-based material forms a solid solution with the manganese-based matrix material, thereby avoiding the formation of a spinel phase of the manganese-based material, improving the stability of the layered structure, and further improving the cycle stability of the positive electrode material.
  • the sodium-manganese-based material has a high conductivity, which also improves the conductivity of the positive electrode material and improves its capacity.
  • the sodium manganese-based material is not simply doped or coated, but forms a solid solution structure with the manganese-based matrix material.
  • it stabilizes the valence state of the Mn element and reduces the Jan-Taylor effect of Mn; on the other hand, it maintains the structure of Mn, reduces the mixing of Li and Mn positions, ensures the stability of the Mn position, and thus improves the structural stability of the positive electrode material, and obtains a positive electrode material with a clear layered structure, avoiding the generation of its spinel phase, thereby stabilizing its cycle stability.
  • the sodium manganese-based material also has excellent electrical conductivity, thereby improving the electrical conductivity of the material, fully and effectively exerting the gram capacity of the positive electrode material, and the cost of the positive electrode material is low, which is convenient for large-scale production.
  • 0.05 ⁇ a ⁇ 0.35 for example 0.05, 0.08, 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33 or 0.35, etc.
  • the numerical range of a is too large, >0.35.
  • the content of LiMn y M (1-y) O2 will be reduced, thereby resulting in a decrease in capacity.
  • an excessively high value of a will cause the Na 2 Mn x R (1-x) O3 phase to be introduced into the bulk phase, increasing the impedance, thereby reducing the kinetics of the overall material, and weakening both the rate performance and the capacity.
  • R in the chemical formula includes Co, Fe, Zn, Cu, Na, K, Zr, Any one of Mg, Nb, W, Y, Sr, Ca or Al, or a combination of at least two thereof.
  • M in the chemical formula includes any one of Ni, Co, Fe, Zn, Cu, Na, K, Zr, Mg, Nb, W, Y, Sr, Ca or Al, or a combination of at least two thereof.
  • the present application provides a method for preparing the manganese-based solid solution positive electrode material as described in the first aspect, the preparation method comprising the following steps:
  • the chemical formula of the sodium manganese-based oxide material is Na 2 Mn x R (1-x) O 3 , 0 ⁇ x ⁇ 1
  • the chemical formula of the manganese-based monosintered material is LiMn y M (1-y) O 2 , 0.1 ⁇ y ⁇ 1
  • R in the chemical formula of the sodium manganese-based oxide material and M in the chemical formula of the manganese-based monocalcined material each independently include an alkaline earth metal element and/or a transition metal element, for example, the x may be 0.05, 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, and the y may be 0.1, 0.13, 0.15, 0.18, 0.2, 0.23, 0.25, 0.28, 0.3, 0.33, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1, and the y may be
  • the sodium manganese-based oxide material and the manganese-based sintered material are sintered and melted together to obtain a solid solution structure, rather than simply presenting it in a coated form.
  • This solid solution structure helps to maintain the stability of the layered structure of the manganese-based positive electrode material during the cycle process and avoid its spinelization, thereby improving the overall cycle performance.
  • the sodium manganese-based oxide material also improves the conductivity of the manganese-based positive electrode material, effectively exerts the capacity of the positive electrode material, and the preparation method is simple, the cost is low, and it is convenient for large-scale production.
  • the sintering temperature is 400-1000°C, for example 400°C, 500°C, 600°C, 700°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, 930°C, 940°C or 950°C, etc., preferably 800-950°C.
  • sintering within the range of 800-950°C can better achieve the fusion of the two phases and the orderly arrangement of the two phases at the atomic size, thereby synthesizing a pure composite phase.
  • the temperature is too low, below 800°C, it is not conducive to the mutual fusion of the two phases, or only partial fusion is formed, and the purity of the phase is reduced.
  • the temperature is too high, above 950°C, it will excessively cause the valence state of Mn to change, which is not conducive to the formation of a layered structure phase, but a spinel phase is formed.
  • the D50 of the sodium manganese-based oxide material is 100 nm to 5 ⁇ m, for example, 100 nm, 300 nm, 500 nm, 800 nm, 1 ⁇ m, 1.3 ⁇ m, 1.5 ⁇ m, 1.8 ⁇ m, 2 ⁇ m, 2.5 ⁇ m, 3 ⁇ m, 3.5 ⁇ m, 4 ⁇ m, 4.5 ⁇ m or 5 ⁇ m.
  • the sodium manganese-based oxide material has a specific surface area of 10 to 40 m 2 /g, for example, 10 m 2 /g, 13 m 2 /g, 15 m 2 /g, 18 m 2 /g, 20 m 2 / g, 23 m 2 /g, 25 m 2 /g, 28 m 2 /g, 30 m 2 /g, 33 m 2 /g, 35 m 2 /g, 38 m 2 /g or 40 m 2 /g.
  • the sodium manganese-based oxide material has a loose structure according to the D50 and specific surface area of the sodium manganese-based oxide material, and the loose structure can ensure that the manganese-based one-sintered material Better interfusion with sodium manganese-based oxide materials helps the two phases form a composite phase at the atomic size.
  • the preparation method of the sodium manganese-based oxide material comprises:
  • the sodium source and the manganese source are mixed and spray-pyrolyzed in an oxygen-containing atmosphere to obtain the sodium manganese-based oxide material.
  • sodium manganese-based oxide material is prepared by a spray pyrolysis method, and a material with a smaller primary particle size can be obtained, so that it has the best activity, which is helpful for subsequent sintering. It also helps to obtain a material with a loose secondary particle structure with a particle size in a suitable range, thereby ensuring the activity of the secondary particles. Since the secondary particles are loose, the primary particles are smaller in size and have higher activity, which helps to achieve the fusion of the two phases under lower temperature sintering to form a solid solution-type composite phase during the subsequent sintering process.
  • the mixed raw materials further include an R source.
  • the molar concentration of the sodium source is 0.1-2 mol/L, for example, 0.1 mol/L, 0.3 mol/L, 0.5 mol/L, 0.8 mol/L, 1 mol/L, 1.3 mol/L, 1.5 mol/L, 1.8 mol/L or 2 mol/L.
  • the sodium source includes any one of sodium citrate, sodium oxalate, sodium acetate, sodium carbonate, sodium hydroxide or sodium oxide, or a combination of at least two thereof.
  • the molar concentration of the manganese source is 0.1-2 mol/L, for example, 0.1 mol/L, 0.3 mol/L, 0.5 mol/L, 0.8 mol/L, 1 mol/L, 1.3 mol/L, 1.5 mol/L, 1.8 mol/L or 2 mol/L.
  • the manganese source includes any one of manganese carbonate, manganese acetate, manganese oxalate or manganese oxide, or a combination of at least two thereof.
  • the temperature of the spray pyrolysis is 400-1000°C, for example, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C, etc.
  • the D50 of the manganese-based sintered material is 1-3 ⁇ m, for example, 1 ⁇ m, 1.3 ⁇ m, 1.5 ⁇ m, 1.8 ⁇ m, 2 ⁇ m, 2.3 ⁇ m, 2.5 ⁇ m, 2.8 ⁇ m or 3 ⁇ m.
  • the D50 of the manganese-based sintered material and the D50 of the sodium manganese-based oxide material match each other and work synergistically, so that the sizes of both materials have better activity, which helps to fuse the two phases under low-temperature sintering, and also helps to synthesize purer materials and avoid the subsequent formation of impurities.
  • the method for preparing the manganese-based sintered material comprises:
  • the manganese source and the lithium source are mixed and sintered once in an oxygen-containing atmosphere to obtain the manganese-based one-sintered material.
  • the mixed raw material also includes an M source.
  • the primary sintering temperature is 400-1000°C, for example, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C.
  • the preparation method comprises the following steps:
  • the mixed raw material also includes a nickel source and an M source, and sintering once at a temperature of 400 to 1000° C. in an oxygen-containing atmosphere to obtain a manganese-based sintered material with a D50 of 1 to 3 ⁇ m;
  • the chemical formula of the sodium manganese-based oxide material is Na 2 Mn x R (1-x) O 3 , 0 ⁇ x ⁇ 1
  • the chemical formula of the manganese-based monosintered material is LiMn y M (1-y) O 2 , 0.1 ⁇ y ⁇ 1
  • R in the chemical formula of the sodium manganese-based oxide material and M in the chemical formula of the manganese-based monosintered material independently include any one or a combination of at least two of alkali metal elements, alkaline earth metal elements or transition metal elements.
  • an embodiment of the present application further provides a lithium-ion battery, wherein the lithium-ion battery comprises the manganese-based solid solution positive electrode material as described in the first aspect.
  • the embodiments of the present application provide a manganese-based solid solution material with a layered structure.
  • the introduction of the sodium manganese-based material forms a solid solution with the manganese-based matrix material, which, on the one hand, stabilizes the valence state of the Mn element and reduces the Jan-Taylor effect of Mn; on the other hand, maintains the structure of Mn, reduces the mixing of Li and Mn sites, ensures the stability of the Mn site, and thus improves the structural stability of the positive electrode material, thereby obtaining a positive electrode material with a significantly layered structure, avoiding the generation of its spinel phase, and thus stabilizing its cycle stability, especially the high-temperature cycle performance.
  • the sodium manganese-based material also has excellent electrical conductivity, thereby improving the electrical conductivity of the material and fully and effectively exerting the gram capacity of the positive electrode material.
  • the button battery adopts the manganese-based solid solution positive electrode material provided by the present application, and limits a in the chemical formula to 0.05 ⁇ a ⁇ 0.35, and at the same time regulates the temperature in the preparation process and the D50 of the material.
  • the gram capacity of the battery can reach more than 170mAh/g, and when the voltage range is 2.5-4.4V, the gram capacity of the battery can reach more than 163mAh/g; within the voltage range of 2.5-4.35V, the gram capacity of the battery can reach more than 140mAh/g, and within the voltage range of 2.5-4.2V, the gram capacity of the battery can reach more than 130mAh/g; under the test conditions of 45°C, 0.1C/0.1C, 2.5-4.35V, the capacity retention rate of the battery after 100 cycles can reach more than 93%.
  • This embodiment provides a manganese-based solid solution positive electrode material.
  • the manganese-based solid solution positive electrode material is a layered structure.
  • the chemical formula of the manganese-based solid solution positive electrode material is 0.35Na 2 MnO 3 ⁇ 0.65LiMnO 2 .
  • the preparation method of the manganese-based solid solution positive electrode material is as follows:
  • Na 2 MnO 3 and LiMnO 2 were prepared respectively by the following methods:
  • Na 2 MnO 3 Sodium acetate and manganese carbonate in the molar ratio of the chemical formula were heated at 650°C in an oxygen atmosphere.
  • LiMnO 2 Manganese oxide and lithium carbonate are mixed in a lithium:manganese molar ratio of 1.05:1, and sintered at 700° C. in an oxygen atmosphere to obtain LiMnO 2 with a D50 of 3 ⁇ m;
  • This embodiment provides a manganese-based solid solution positive electrode material.
  • the manganese-based solid solution positive electrode material is a layered structure.
  • the chemical formula of the manganese-based solid solution positive electrode material is 0.1Na 2 MnO 3 ⁇ 0.9LiMnO 2 .
  • the preparation method of the manganese-based solid solution positive electrode material is as follows:
  • Na 2 MnO 3 and LiMnO 2 are prepared respectively by the following preparation methods:
  • Na 2 MnO 3 Sodium acetate and manganese carbonate were spray pyrolyzed at 400° C. in an oxygen atmosphere at a molar ratio of the chemical formula to obtain Na 2 MnO 3 having a D50 of 4 ⁇ m and a specific surface area of 25 m 2 /g;
  • LiMnO 2 Manganese carbonate and lithium carbonate are mixed in a lithium:manganese molar ratio of 1.03:1, and sintered at 900° C. in an oxygen atmosphere to obtain LiMnO 2 with a D50 of 2 ⁇ m;
  • This embodiment provides a manganese-based solid solution positive electrode material.
  • the manganese-based solid solution positive electrode material is a layered structure.
  • the chemical formula of the manganese-based solid solution positive electrode material is 0.25Na 2 Mn 0.6 Zr 0.4 O 3 ⁇ 0.75LiMnO 2 .
  • the preparation method of the manganese-based solid solution positive electrode material is as follows:
  • Na 2 Mn 0.6 Zr 0.4 O 3 and LiMnO 2 were prepared respectively by the following methods:
  • Na 2 Mn 0.6 Zr 0.4 O 3 Sodium acetate, manganese carbonate and zirconium acetate were spray pyrolyzed at 800° C. in an oxygen atmosphere at a molar ratio of the chemical formula to obtain Na 2 MnO 3 having a D50 of 1.5 ⁇ m and a specific surface area of 30 m 2 /g;
  • LiMnO 2 Manganese oxide and lithium carbonate are mixed in a lithium:manganese molar ratio of 1.01:1, and sintered at 700° C. in an oxygen atmosphere to obtain LiMnO 2 with a D50 of 1 ⁇ m;
  • the difference between this embodiment and embodiment 1 is that the sintering temperature in step (2) of this embodiment is 750°C.
  • step (2) of this embodiment is 1000°C.
  • step (1) of this embodiment the D50 of LiMnO 2 is 4 ⁇ m.
  • This embodiment provides a manganese-based solid solution positive electrode material.
  • the manganese-based solid solution positive electrode material is a layered structure.
  • the chemical formula of the manganese-based solid solution positive electrode material is 0.1Na 2 MnO 3 ⁇ 0.9LiMn 0.5 Ni 0.5 O 2 .
  • the preparation method of the manganese-based solid solution positive electrode material is as follows:
  • Na 2 MnO 3 and LiMn 0.5 Ni 0.5 O 2 were prepared respectively by the following methods:
  • Na 2 MnO 3 Sodium acetate and manganese carbonate were spray pyrolyzed at 650° C. in an oxygen atmosphere to obtain Na 2 MnO 3 with a D50 of 5 ⁇ m and a specific surface area of 10 m 2 /g;
  • LiMn 0.5 Ni 0.5 O 2 Manganese oxide, nickel hydroxide and lithium carbonate are mixed in a molar ratio of lithium: manganese: nickel of 1.05:0.5:0.5, and sintered at 700° C. in an oxygen atmosphere to obtain LiMn 0.5 Ni 0.5 O 2 with a D50 of 2.5 ⁇ m;
  • Example 1 The difference between this comparative example and Example 1 is that the positive electrode material in this comparative example is pure LiMnO 2 , and the preparation method only carries out the preparation process of LiMnO 2 in step (1).
  • This comparative example provides a manganese-based positive electrode material with an aluminum oxide-coated LiMnO2 core, and the preparation method of the positive electrode material is as follows:
  • LiMnO 2 Manganese oxide and lithium carbonate are mixed in a lithium:manganese molar ratio of 1.05:1, and sintered at 700° C. in an oxygen atmosphere to obtain LiMnO 2 with a D50 of 3 ⁇ m;
  • Example 9 The difference between this comparative example and Example 9 is that the positive electrode material in this comparative example is pure LiMn 0.5 Ni 0.5 O 2 . In the preparation method, only the preparation process of LiMn 0.5 Ni 0.5 O 2 in step (1) is carried out.
  • the positive electrode materials provided in Examples 1-9 and Comparative Examples 1-3 were mixed with conductive carbon black, polyvinylidene fluoride and N-methylpyrrolidone to obtain positive electrode slurry, which was coated on the surface of aluminum foil and dried and rolled to obtain positive electrode plates.
  • a positive electrode plate with a diameter of 12 mm was placed in a positive electrode shell with an inner diameter of 18 mm, 100 uL of electrolyte was injected, and a 16 um 16 um diaphragm was added.
  • a 14 um lithium sheet was placed on the diaphragm, and then a gasket was added, and then the negative electrode shell was covered to form a buckle battery, and the electrochemical performance test was carried out under the following test conditions:
  • Example 1 From the data results of Example 1 and Examples 4 and 5, it can be seen that the value of a is too large, exceeding 0.35, that is, the proportion of sodium manganese-based oxide material is too large, which is not conducive to capacity utilization, and the capacity is also low under high voltage, but the cycle will improve, which also proves that the sodium manganese phase helps to improve the cycle of the overall material.
  • step (2) i.e., the process of mixing and melting to obtain a solid solution
  • step (3) i.e., the process of mixing and melting to obtain a solid solution
  • the temperature is too low, it will affect the fusion of the two phases, which is not conducive to the formation of a solid solution, resulting in a significant decrease in the gram capacity and no improvement in the cycle.
  • the temperature is too high, the pure manganese-based material will change, the two phases will be difficult to fuse, and the capacity will be reduced and the cycle will deteriorate.
  • Example 1 From the data results of Example 1 and Example 8, it can be seen that the D50 of the manganese-based sintered material and the D50 of the sodium manganese-based oxide material must match each other. If they do not match, it will affect the fusion of the two phases, resulting in a decrease in the material purity of the resulting solid solution structure, ultimately leading to a decrease in capacity and a weakening of the cycle performance.
  • Example 1 and Comparative Example 1, and Example 9 and Comparative Example 3 From the data results of Example 1 and Comparative Example 1, and Example 9 and Comparative Example 3, it can be seen that the pure manganese-based positive electrode material has low gram capacity and poor cycle performance, and the use of sodium manganese-based materials for solid solution treatment helps to increase the gram capacity of the material and improve the cycle performance, which is a very promising material. From the data results of Example 1 and Comparative Example 2, it can be seen that the conventional treatment process still cannot solve the problems of room temperature cycle and poor gram capacity of manganese-based materials, and the solid solution of sodium manganese-based materials, rather than simple coating or doping, stabilizes the manganese-based materials from the bulk structure, thereby increasing the gram capacity of the manganese-based positive electrode material and improving its cycle performance.
  • the present application provides a manganese-based solid solution material with a layered structure.
  • the introduction of the sodium manganese-based material forms a solid solution with the manganese-based matrix material, avoiding the formation of the spinel phase of the manganese-based material, improving the stability of the layered structure, and further improving the cycle stability of the positive electrode material, especially the high-temperature cycle stability.
  • the sodium manganese-based material has a high conductivity, which also improves the conductivity of the positive electrode material and improves its capacity.
  • the button battery adopts the manganese-based solid solution positive electrode material provided by the present application, and limits a in the chemical formula to 0.05 ⁇ a ⁇ 0.35, and at the same time regulates the temperature in the preparation process and the D50 of the material.
  • the gram capacity of the battery can reach more than 170mAh/g, and when the voltage range is 2.5-4.4V, the gram capacity of the battery can reach more than 163mAh/g; within the voltage range of 2.5-4.35V, the gram capacity of the battery can reach more than 140mAh/g, and within the voltage range of 2.5-4.2V, the gram capacity of the battery can reach more than 130mAh/g; under the test conditions of 45°C, 0.1C/0.1C, 2.5-4.35V, the capacity retention rate of the battery after 100 cycles can reach more than 93%.

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Abstract

本申请提供了一种锰基固溶体正极材料及制备方法与用途。所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为aNa2MnxR(1-x)O3·(1-a)LiMnyM(1-y)O2，其中0.05≤a＜1，0＜x≤1，0.1≤y≤1，所述化学式中的R和M各自独立地包括碱金属元素、碱土金属元素或过渡金属元素中的任意一种或至少两种的组合。本申请提供了一种层状结构的锰基固溶体材料，钠锰基材料的引入，与锰基基体材料形成了固溶体，避免了锰基材料的尖晶石相的形成，提升了层状结构的稳定性，进而提升了正极材料的循环稳定性，且钠锰基材料导电性较高，还提升了正极材料的导电性，其容量得到了提高。

Description

一种锰基固溶体正极材料及制备方法与用途 技术领域
本申请实施例涉及锂离子电池技术领域，例如一种锰基固溶体正极材料及制备方法与用途。
背景技术
锰基材料LiMnO2理论容量285mAh/g，容量发挥潜力大，同时具有成本低，原料丰富，安全性能优等优势，但是高温性能较差需要找到合适的方案来稳定其结构避免其尖晶石化。
目前锰基材料LiMnO2难以合成纯相，大部分合成出来的材料容易尖晶石化，并且克容量发挥较低高温循环较差，常用的方法是采用掺杂元素和包覆等方案来稳定其结构，都是单个元素占据Li/Mn/O位，但是在长期的充放电过程中掺杂元素也会慢慢的不稳定；都难以从根本上改变LiMnO2材料本身层状结构不稳定的特点，高温下性能依然无法满足要求；同时在循环过程中LiMnO2会逐渐倾向于尖晶石化，而失去活性，容量无法恢复。
目前通过如下方法对锰基材料进行改性，(1)CN102800840A公开了一种类球形锰酸锂及其制备方法，减小了材料的比表面积，从而减少了锰的溶解，提高了电池的循环性能。但是这种方法只是对于材料形貌进行了调控，没有能够有效隔绝锰酸锂和电解液的直接接触。(2)表面包覆氧化物、磷酸盐、氟化物等无机材料，通过惰性材料的包覆，隔绝正极材料与电解液的直接接触，减少了锰的溶解，提高了电池的循环性。如CN104134793A公开了一种锂离子电池正极材锰酸锂的制备方法，使用掺杂改性锰酸锂包覆普通锰酸锂，可以提高材料的循环性能。但是掺杂改性的锰酸锂在生产过程中容易引入晶体缺陷，导致产品一致性较差，而且这种改性方法对锰酸锂表面发生的副反应减弱的程度影响有效。如CN102054985A公开了一种锰酸锂及其制备方法，通过包覆Li、Cr、Co、Ni、Mg、Ga、Sr、Ba、Na、K、Al、Be、B、Ti、Zr、Cu、Zn、Ga、Sn、V或F、Cl、Br、I、S等元素，改善了材料与电解液的相容性，从而改善了高温及常温循环性能和高温存储性能。这种方法在结晶度高的前驱体表面包覆了低结晶度的化合物，因为两种材料的晶体结构不同，包覆材料和内核材料之间会形成新的晶界。极片辊压过程中，会由于锰酸锂材料内部应力较大而发生破裂，导致电池循环性能变差。
因此，如何有效地避免锰基正极材料的尖晶石化，提升材料的容量同时提升循环性能，是亟待解决的技术问题。
发明内容
以下是对本文详细描述的主题的概述。本概述并非是为了限制权利要求的保护范围。
本申请实施例提供一种锰基固溶体正极材料及制备方法与用途。本申请实施例提供了一种层状结构的锰基固溶体材料，钠锰基材料的引入，与锰基基体材料形成了固溶体，避免了锰基材料的尖晶石相的形成，提升了层状结构的稳定性，进而提升了正极材料的循环稳定性，且钠锰基材料导电性较高，还提升了正极材料的导电性，其容量得到了提高。
第一方面，本申请实施例提供一种锰基固溶体正极材料，所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为aNa2MnxR(1-x)O3·(1-a)LiMnyM(1-y)O2，其中0.05≤a＜1，0＜x≤1，0.1≤y≤1，所述化学式中的R和M各自独立地包括碱金属元素、碱土金属元素或过渡金属元素中的任意一种或至少两种的组合。
例如，所述a可以为0.05、0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9或0.99等；所述x可以为0.05、0.1、0.13、0.15、0.18、0.2、0.23、0.25、0.28、0.3、0.33、0.35、0.4、0.5、0.6、0.7、0.8、0.9或1等，所述y可以为0.1、0.13、0.15、0.18、0.2、0.23、0.25、0.28、0.3、0.33、0.35、0.4、0.5、0.6、0.7、0.8、0.9或1等。
本申请提供了一种层状结构的锰基固溶体材料，钠锰基材料的引入，与锰基基体材料形成了固溶体，避免了锰基材料的尖晶石相的形成，提升了层状结构的稳定性，进而提升了正极材料的循环稳定性，且钠锰基材料导电性较高，还提升了正极材料的导电性，其容量得到了提高。
本申请中，钠锰基材料，并非是单纯的掺杂或者包覆，而是与锰基基体材料形成了固溶体结构，一方面稳定了Mn元素的价态，减少了Mn的姜泰勒效应；另一方面维持了Mn的结构，减少Li位和Mn位的混排，保证了Mn位的稳定，进而提升了正极材料的结构稳定性，得到了明显地层状结构的正极材料，避免了其尖晶石相的产生，进而稳定了其循环稳定性，同时钠锰基材料还具有优异的导电性，从而提升了材料的导电性，充分有效地发挥了正极材料的克容量，且正极材料的成本低廉，便于规模化生产。
在一实施例中，所述化学式中，0.05≤a≤0.35，例如0.05、0.08、0.1、0.13、0.15、0.18、0.2、0.23、0.25、0.28、0.3、0.33或0.35等。
本申请提供的锰基固溶体正极材料的化学式中，a的数值范围过大，＞0.35，一方面会使得LiMnyM(1-y)O2的含量减少，从而导致容量降低，另一方面过高的a值，使得Na2MnxR(1-x)O3相导入体相中，阻抗增加，使得整体材料的动力学降低，倍率性能和容量均弱化。
在一实施例中，所述化学式中的R包括Co、Fe、Zn、Cu、Na、K、Zr、 Mg、Nb、W、Y、Sr、Ca或Al中的任意一种或至少两种的组合。
在一实施例中，所述化学式中的M包括Ni、Co、Fe、Zn、Cu、Na、K、Zr、Mg、Nb、W、Y、Sr、Ca或Al中的任意一种或至少两种的组合。
第二方面，本申请提供一种如第一方面所述的锰基固溶体正极材料的制备方法，所述制备方法包括以下步骤：
将钠锰基氧化物材料与锰基一烧材料混合，含氧气氛下烧结，得到所述锰基固溶体正极材料；
其中，所述钠锰基氧化物材料的化学式为Na2MnxR(1-x)O3，0＜x≤1，所述锰基一烧材料的化学式为LiMnyM(1-y)O2，0.1≤y≤1，所述钠锰基氧化物材料的化学式中的R和所述锰基一烧材料的化学式中的M各自独立地包括碱土金属元素和/或过渡金属元素，例如，所述x可以为0.05、0.1、0.13、0.15、0.18、0.2、0.23、0.25、0.28、0.3、0.33、0.35、0.4、0.5、0.6、0.7、0.8、0.9或1等，所述y可以为0.1、0.13、0.15、0.18、0.2、0.23、0.25、0.28、0.3、0.33、0.35、0.4、0.5、0.6、0.7、0.8、0.9或1等。
本申请中，钠锰基氧化物材料与锰基一烧材料经过烧结，相互熔融，得到了固溶体结构，而非单纯的以包覆形态呈现，这一固溶体结构的出现，有助于循环过程中保持锰基正极材料的层状结构的稳定性，避免其尖晶石化，从而提升了整体的循环性能，且钠锰基氧化物材料还提升了锰基正极材料的导电性，有效地发挥了正极材料的容量，且制备方法简单，成本较低，便于大规模生产。
在一实施例中，所述烧结的温度为400～1000℃，例如400℃、500℃、600℃、700℃、800℃、810℃、820℃、830℃、840℃、850℃、860℃、870℃、880℃、890℃、900℃、910℃、920℃、930℃、940℃或950℃等，优选为800～950℃。
本申请中，在800～950℃的范围内烧结，可更好地实现两种相的融合，实现原子尺寸上，两种相的有序排列，从而合成纯的复合物相，而温度过低，低于800℃，不利于两种相的相互融合，或者只形成部分融合，物相纯度降低，而温度过高，高于950℃，又会过度导致Mn的价态变化，不利于形成层状结构物相，而形成尖晶石相。。
在一实施例中，所述钠锰基氧化物材料的D50为100nm～5μm，例如100nm、300nm、500nm、800nm、1μm、1.3μm、1.5μm、1.8μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm或5μm等。
在一实施例中，所述钠锰基氧化物材料的比表面积为10～40m2/g，例如10m2/g、13m2/g、15m2/g、18m2/g、20m2/g、23m2/g、25m2/g、28m2/g、30m2/g、33m2/g、35m2/g、38m2/g或40m2/g等。
本申请中，通过钠锰基氧化物材料的D50和比表面积，表面本申请中的钠锰基氧化物材料为疏松结构，而疏松结构在烧结过程中可以保证锰基一烧材料 更好与钠锰基氧化物材料互熔，有助于两种相在原子尺寸上形成复合相。
在一实施例中，所述钠锰基氧化物材料的制备方法包括：
将钠源和锰源混合，含氧气氛下喷雾热解，得到所述钠锰基氧化物材料。
本申请中，通过喷雾热解的方法制备钠锰基氧化物材料，可得到一次颗粒尺寸较小的材料，从而具有最好的活性，有助于后续烧结，同时也有助于获得二次颗粒疏松结构的物质，粒径在合适范围，从而保证了二次颗粒的活性，由于二次颗粒疏松，一次颗粒尺寸较小，活性高，有助于后续烧结过程中，实现较低温度烧结下两相融合形成固溶体型的复合相。
在一实施例中，所述混合的原料还包括R源。
优选地，所述钠源的摩尔浓度为0.1～2mol/L，例如0.1mol/L、0.3mol/L、0.5mol/L、0.8mol/L、1mol/L、1.3mol/L、1.5mol/L、1.8mol/L或2mol/L等。
优选地，所述钠源包括柠檬酸钠、草酸钠、乙酸钠、碳酸钠、氢氧化钠或氧化钠中的任意一种或至少两种的组合。
优选地，所述锰源的摩尔浓度为0.1～2mol/L，例如0.1mol/L、0.3mol/L、0.5mol/L、0.8mol/L、1mol/L、1.3mol/L、1.5mol/L、1.8mol/L或2mol/L等。
优选地，所述锰源包括碳酸锰、乙酸锰、草酸锰或氧化锰中的任意一种或至少两种的组合。
优选地，所述喷雾热解的温度为400～1000℃，例如400℃、450℃、500℃、550℃、600℃、650℃、700℃、750℃、800℃、850℃、900℃、950℃或1000℃等。
在一实施例中，所述锰基一烧材料的D50为1～3μm，例如1μm、1.3μm、1.5μm、1.8μm、2μm、2.3μm、2.5μm、2.8μm或3μm等。
本申请中，锰基一烧材料的D50与钠锰基氧化物材料的D50相互匹配，协同作用，使得两种材料的尺寸均具有较优的活性，有助于低温烧结下两相的融合，同时也有助于合成出较纯的材料，避免后续形成杂相。
在一实施例中，所述锰基一烧材料的制备方法包括：
将锰源和锂源混合，含氧气氛下进行一次烧结，得到所述锰基一烧材料。
在一实施例中，所述混合的原料还包括M源。
优选地，所述一次烧结的温度为400～1000℃，例如400℃、450℃、500℃、550℃、600℃、650℃、700℃、750℃、800℃、850℃、900℃、950℃或1000℃等。
作为优选的技术方案，所述制备方法包括以下步骤：
(1)将摩尔浓度为0.1～2mol/L钠源和摩尔浓度为0.1～2mol/L的锰源混合，其中，混合的原料还包括R源，含氧气氛下以400～1000℃的温度进行喷雾热解，得到D50为100nm～5μm、比表面积为10～40m2/g为的钠锰基氧化物材料；
将锰源和锂源混合，其中，混合的原料中还包括镍源和M源，含氧气氛下以400～1000℃的温度进行一次烧结，得到D50为1～3μm的锰基一烧材料；
(2)将钠锰基氧化物材料与锰基一烧材料混合，含氧气氛下以800～950℃的温度烧结，得到所述锰基固溶体正极材料；
其中，所述钠锰基氧化物材料的化学式为Na2MnxR(1-x)O3，0＜x≤1，所述锰基一烧材料的化学式为LiMnyM(1-y)O2，0.1≤y≤1，所述钠锰基氧化物材料的化学式中的R和所述锰基一烧材料的化学式中的M各自独立地包括包括碱金属元素、碱土金属元素或过渡金属元素中的任意一种或至少两种的组合。
第三方面，本申请实施例还提供一种锂离子电池，所述锂离子电池包括如第一方面所述的锰基固溶体正极材料。
与相关技术相比，本申请实施例具有以下有益效果：
(1)本申请实施例提供了一种层状结构的锰基固溶体材料，钠锰基材料的引入，与锰基基体材料形成了固溶体，一方面稳定了Mn元素的价态，减少了Mn的姜泰勒效应；另一方面维持了Mn的结构，减少Li位和Mn位的混排，保证了Mn位的稳定，进而提升了正极材料的结构稳定性，得到了明显地层状结构的正极材料，避免了其尖晶石相的产生，进而稳定了其循环稳定性尤其是高温循环性能，同时钠锰基材料还具有优异的导电性，从而提升了材料的导电性，充分有效地发挥了正极材料的克容量。扣式电池采用本申请提供的锰基固溶体正极材料，且限制化学式中a的0.05≤a≤0.35，同时调控制备过程中的温度与材料的D50，常温在在0.1C的充放电电流下，2.5～4.5V的电压范围时，电池的克容量可达170mAh/g以上，2.5～4.4V的电压范围时，电池的克容量可达163mAh/g以上；2.5～4.35V的电压范围内，电池的克容量可达140mAh/g以上，2.5～4.2V的电压范围内，电池的克容量可达130mAh/g以上；45℃高温下，0.1C/0.1C，2.5～4.35V的测试条件下，电池循环100圈后的容量保持率可达93％以上。
(2)本申请实施例提供的制备方法简单可行，成本较低，便于大规模生产。
在阅读并理解了详细描述后，可以明白其他方面。
具体实施方式
实施例1
本实施例提供一种锰基固溶体正极材料，所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为0.35Na2MnO3·0.65LiMnO2。
所述锰基固溶体正极材料的制备方法如下：
(1)分别制备得到Na2MnO3和LiMnO2，制备方法为：
Na2MnO3：将乙酸钠和碳酸锰以化学式的摩尔比在氧气气氛下以650℃的温 度通过喷雾热解得到D50为5μm、比表面积为10m2/g的Na2MnO3；
LiMnO2：将氧化锰和碳酸锂以锂:锰的摩尔比为1.05:1的比例混合，氧气气氛下以700℃的温度烧结，得到D50为3μm的LiMnO2；
(2)将Na2MnO3和LiMnO2以0.35:0.65的摩尔比混合，氧气气氛下以800℃的温度烧结，得到所述锰基正极材料。
实施例2
本实施例提供一种锰基固溶体正极材料，所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为0.1Na2MnO3·0.9LiMnO2。
所述锰基固溶体正极材料的制备方法如下：
(1)分别制备得到Na2MnO3和LiMnO2，制备方法为：
Na2MnO3：将乙酸钠和碳酸锰以化学式的摩尔比在氧气气氛下以400℃的温度通过喷雾热解得到D50为4μm、比表面积为25m2/g的Na2MnO3；
LiMnO2：将碳酸锰和碳酸锂以锂:锰的摩尔比为1.03:1的比例混合，氧气气氛下以900℃的温度烧结，得到D50为2μm的LiMnO2；
(2)将Na2MnO3和LiMnO2以0.1:0.9的摩尔比混合，氧气气氛下以870℃的温度烧结，得到所述锰基正极材料。
实施例3
本实施例提供一种锰基固溶体正极材料，所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为0.25Na2Mn0.6Zr0.4O3·0.75LiMnO2。
所述锰基固溶体正极材料的制备方法如下：
(1)分别制备得到Na2Mn0.6Zr0.4O3和LiMnO2，制备方法为：
Na2Mn0.6Zr0.4O3：将乙酸钠、碳酸锰和乙酸锆以化学式的摩尔比在氧气气氛下以800℃的温度通过喷雾热解得到D50为1.5μm、比表面积为30m2/g的Na2MnO3；
LiMnO2：将氧化锰和碳酸锂以锂:锰的摩尔比为1.01:1的比例混合，氧气气氛下以700℃的温度烧结，得到D50为1μm的LiMnO2；
(2)将Na2Mn0.6Zr0.4O3和LiMnO2以0.25:0.75的摩尔比混合，氧气气氛下以950℃的温度烧结，得到所述锰基正极材料。
实施例4
本实施例与实施例1的区别为本实施例中固溶体的化学式为0.4Na2MnO3·0.6LiMnO2，制备方法中适应性调整摩尔比即可。
其余制备方法与参数与实施例1保持一致。
实施例5
本实施例与实施例1的区别为本实施例中固溶体的化学式为0.9Na2MnO3·0.1LiMnO2，制备方法中适应性调整摩尔比即可。
其余制备方法与参数与实施例1保持一致。
实施例6
本实施例与实施例1的区别为，本实施例步骤(2)中的烧结温度为750℃。
其余制备方法与参数与实施例1保持一致。
实施例7
本实施例与实施例1的区别为，本实施例步骤(2)中的烧结温度为1000℃。
其余制备方法与参数与实施例1保持一致。
实施例8
本实施例与实施例1的区别为，本实施例步骤(1)中LiMnO2的D50为4μm。
其余制备方法与参数与实施例1保持一致。
实施例9
本实施例提供一种锰基固溶体正极材料，所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为0.1Na2MnO3·0.9LiMn0.5Ni0.5O2。
所述锰基固溶体正极材料的制备方法如下：
(1)分别制备得到Na2MnO3和LiMn0.5Ni0.5O2，制备方法为：
Na2MnO3：将乙酸钠和碳酸锰在氧气气氛下以650℃的温度通过喷雾热解得到D50为5μm、比表面积为10m2/g的Na2MnO3；
LiMn0.5Ni0.5O2：将氧化锰、氢氧化镍和碳酸锂以锂:锰:镍的摩尔比为1.05:0.5:0.5的比例混合，氧气气氛下以700℃的温度烧结，得到D50为2.5μm的LiMn0.5Ni0.5O2；
(2)将Na2MnO3和LiMn0.5Ni0.5O2以0.1:0.9的摩尔比混合，氧气气氛下以800℃的温度烧结，得到所述锰基正极材料。
对比例1
本对比例与实施例1的区别为，本对比例中为纯LiMnO2正极材料，制备方法中只进行步骤(1)中LiMnO2的制备过程。
其余制备方法与参数与实施例1保持一致。
对比例2
本对比例提供一种氧化铝包覆LiMnO2内核的锰基正极材料，所述正极材料的制备方法如下：
LiMnO2：将氧化锰和碳酸锂以锂:锰的摩尔比为1.05:1的比例混合，氧气气氛下以700℃的温度烧结，得到D50为3μm的LiMnO2；
再采用500nm的氧化铝和LiMnO2进行混合包覆制备得到D50为3μm的铝包覆的LiMnO2材料；
对比例3
本对比例与实施例9的区别为，本对比例中为纯LiMn0.5Ni0.5O2正极材料， 制备方法中只进行步骤(1)中LiMn0.5Ni0.5O2的制备过程。
其余制备方法与参数与实施例9保持一致。
将实施例1-9与对比例1-3提供的正极材料与导电炭黑、聚偏氟乙烯和N-甲基吡咯烷酮混合，得到正极浆料，涂覆于铝箔表面，干燥辊压后得到正极极片，将直径12mm正极极片放入内径18mm正极壳中，注入100uL电解液再加上16um的16um隔膜，再在隔膜上面放14um的锂片，然后加上垫片，再盖上负极壳，组成扣电，进行电化学性能测试，测试条件为：
(1)分别在2.5～4.2V、2.5～4.35V、2.5V～4.4V、2.5～4.5V的电压下以0.1C的充放电电流进行克容量的测试；
(2)45℃下以2.5～4.35V的电压和1C的电流进行100圈循环性能测试；
测试结果如表1所示：
表1

从实施例1与实施例4和5的数据结果可知，a的数值过大，超过0.35，即钠锰基氧化物材料的占比过大，不利于容量发挥，高电压下容量也较低，但是循环会改善，也证明了钠锰相有助于提升整体材料的循环。
从实施例1与实施例6和7的数据结果可知，步骤(2)即混合熔融得到固溶体的过程中，温度过低，会影响两相融合，不利于固溶体形成，导致克容量明显降低，同时循环没有改善，而温度过高，又会导致纯锰基材料发生改变，两相难以融合，同时容量降低，循环变差。
从实施例1与实施例8的数据结果可知，锰基一烧材料的D50与钠锰基氧化物材料的D50要相互匹配，如果不匹配会影响两相的融合，使得所得固溶体结构的材料纯度降低，最终导致容量降低，循环性能减弱。
从实施例1与对比例1，实施例9与对比例3的数据结果可知，纯锰基正极材料克容量低，循环性能差，而采用钠锰基材料进行固溶处理后，有助于提升材料的克容量，有助于改善循环性能，是非常具有潜力的材料。从实施例1与对比例2的数据结果可知，常规的处理过程，依然无法解决锰基材料的常温循环和克容量较差的问题，而通过钠锰基材料固溶，不是简单的包覆或掺杂，从体相结构上稳定了锰基材料，从而提升锰基正极材料的克容量并改善了其循环性能。
综上所述，本申请提供了一种层状结构的锰基固溶体材料，钠锰基材料的引入，与锰基基体材料形成了固溶体，避免了锰基材料的尖晶石相的形成，提升了层状结构的稳定性，进而提升了正极材料的循环稳定性尤其是高温循环稳定性，且钠锰基材料导电性较高，还提升了正极材料的导电性，其容量得到了提高。扣式电池采用本申请提供的锰基固溶体正极材料，且限制化学式中a的0.05≤a≤0.35，同时调控制备过程中的温度与材料的D50，常温在在0.1C的充放电电流下，2.5～4.5V的电压范围时，电池的克容量可达170mAh/g以上，2.5～4.4V的电压范围时，电池的克容量可达163mAh/g以上；2.5～4.35V的电压范围内，电池的克容量可达140mAh/g以上，2.5～4.2V的电压范围内，电池的克容量可达130mAh/g以上；45℃高温下，0.1C/0.1C，2.5～4.35V的测试条件下，电池循环100圈后的容量保持率可达93％以上。

Claims (15)

  1. 一种锰基固溶体正极材料，其中，所述锰基固溶体正极材料为层状结构，所述锰基固溶体正极材料的化学式为aNa2MnxR(1-x)O3·(1-a)LiMnyM(1-y)O2，其中0.05≤a＜1，0＜x≤1，0.1≤y≤1，所述化学式中的R和M各自独立地包括碱金属元素、碱土金属元素或过渡金属元素中的任意一种或至少两种的组合。
  2. 根据权利要求1所述的锰基固溶体正极材料，其中，所述化学式中，0.05≤a≤0.35。
  3. 根据权利要求1或2所述的锰基固溶体正极材料，其中，所述化学式中的R包括Co、Fe、Zn、Cu、Na、K、Zr、Mg、Nb、W、Y、Sr、Ca或Al中的任意一种或至少两种的组合。
  4. 根据权利要求1-3任一项所述的锰基固溶体正极材料，其中，所述化学式中的M包括Ni、Co、Fe、Zn、Cu、Na、K、Zr、Mg、Nb、W、Y、Sr、Ca或Al中的任意一种或至少两种的组合。
  5. 一种如权利要求1-4任一项所述的锰基固溶体正极材料的制备方法，其包括以下步骤：
    将钠锰基氧化物材料与锰基一烧材料混合，含氧气氛下烧结，得到所述锰基固溶体正极材料；
    其中，所述钠锰基氧化物材料的化学式为Na2MnxR(1-x)O3，0＜x≤1，所述锰基一烧材料的化学式为LiMnyM(1-y)O2，0.1≤y≤1，所述钠锰基氧化物材料的化学式中的R和所述锰基一烧材料的化学式中的M各自独立地包括碱土金属元素和/或过渡金属元素。
  6. 根据权利要求5所述的锰基固溶体正极材料的制备方法，其中，所述烧结的温度为400～1000℃，优选为800～950℃。
  7. 根据权利要求5或6所述的锰基固溶体正极材料的制备方法，其中，所述钠锰基氧化物材料的D50为100nm～5μm。
  8. 根据权利要求5-7任一项所述的锰基固溶体正极材料的制备方法，其中，所述钠锰基氧化物材料的比表面积为10～40m2/g。
  9. 根据权利要求5-8任一项所述的锰基固溶体正极材料的制备方法，其中，所述钠锰基氧化物材料的制备方法包括：
    将钠源和锰源混合，含氧气氛下喷雾热解，得到所述钠锰基氧化物材料。
  10. 根据权利要求9所述的锰基固溶体正极材料的制备方法，其中，所述混合的原料还包括R源；
    优选地，所述钠源的摩尔浓度为0.1～2mol/L；
    优选地，所述钠源包括柠檬酸钠、草酸钠、乙酸钠、碳酸钠、氢氧化钠或氧化钠中的任意一种或至少两种的组合；
    优选地，所述锰源的摩尔浓度为0.1～2mol/L；
    优选地，所述锰源包括碳酸锰、乙酸锰、草酸锰或氧化锰中的任意一种或至少两种的组合；
    优选地，所述喷雾热解的温度为400～1000℃。
  11. 根据权利要求5-10任一项所述的锰基固溶体正极材料的制备方法，其中，所述锰基一烧材料的D50为1～3μm。
  12. 根据权利要求5-11任一项所述的锰基固溶体正极材料的制备方法，其中，所述锰基一烧材料的制备方法包括：
    将锰源和锂源混合，含氧气氛下进行一次烧结，得到所述锰基一烧材料。
  13. 根据权利要求12所述的锰基固溶体正极材料的制备方法，其中，所述混合的原料还包括M源；
    优选地，所述一次烧结的温度为400～1000℃。
  14. 根据权利要求5-13任一项所述的锰基固溶体正极材料的制备方法，其包括以下步骤：
    (1)将摩尔浓度为0.1～2mol/L钠源和摩尔浓度为0.1～2mol/L的锰源混合，其中，混合的原料还包括R源，含氧气氛下以400～1000℃的温度进行喷雾热解，得到D50为100nm～5μm、比表面积为10～40m2/g为的钠锰基氧化物材料；
    将锰源和锂源混合，其中，混合的原料中还包括镍源和M源，含氧气氛下以400～1000℃的温度进行一次烧结，得到D50为1～3μm的锰基一烧材料；
    (2)将钠锰基氧化物材料与锰基一烧材料混合，含氧气氛下以800～950℃的温度烧结，得到所述锰基固溶体正极材料；
    其中，所述钠锰基氧化物材料的化学式为Na2MnxR(1-x)O3，0＜x≤1，所述锰基一烧材料的化学式为LiMnyM(1-y)O2，0.1≤y≤1，所述钠锰基氧化物材料的化学式中的R和所述锰基一烧材料的化学式中的M各自独立地包括包括碱金属元素、碱土金属元素或过渡金属元素中的任意一种或至少两种的组合。
  15. 一种锂离子电池，其中，所述锂离子电池包括如权利要求1-4任一项所述的锰基固溶体正极材料。
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