Lithium-rich manganese oxide positive electrode material, its manufacturing method and use, positive electrode sheet and use thereof

Abstract

The present invention relates to the technical field of lithium ion batteries, and discloses a lithium-rich manganese oxide cathode material, its manufacturing method and use, and a cathode sheet and its use. The chemical composition of the cathode material is as follows: xLi[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2·(1-x)LiMn 1-b M′ b O2, The XRD spectrum of the positive electrode material shows a diffraction peak P within the range of diffraction angle 2θ1 [43.5(1-x)+44x]°≦2θ1≦[44(1-x)+45x]°. (1) The XRD spectrum of the positive electrode material shows a diffraction peak P within the range of diffraction angle 2θ2 [17.7(1-x)+18.3x]°≦2θ2≦[19.2(1-x)+19.8x]°. (2) where x is 0.35≦x≦0.63. The positive electrode material has high initial efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance.

Description

[Technical Field]

[0001] The present invention relates to the field of lithium ion battery technology, and in particular to a lithium-rich manganese oxide cathode material and its preparation and use, and a cathode sheet and its use. [Background technology]

[0002] In recent years, new energy vehicles have shown favorable conditions for vigorous development as a national strategic emerging industry to address environmental pollution and the energy crisis, and lithium-ion batteries, as a new energy carrier with excellent comprehensive performance, have been widely applied in markets such as electric vehicles, energy storage power plants, communications and digital electronic products.

[0003] In lithium-ion batteries, the cathode is the core material of the lithium-ion battery, which directly determines the technical performance level of the battery. The traditional lithium-ion cathode material is LiCoO2, which is expensive and mainly used in 3C digital electronic products, and polyvalent LiNi 1-x-y Co x Mn y O2 and LiNi 1-x-y Co x Al y O2, due to its synergistic effect with other elements, has significantly improved cycling performance and is widely used in new energy power batteries. However, its energy density no longer meets people's needs for long battery life. LiFePO4, with its advantages of low cost, high safety, and long cycling life, is primarily used in power batteries and energy storage, but its low specific capacity, close to the theoretical value, makes it difficult to break through. LiMn2O4, with its low cost, is prone to manganese dissolution and the Jahn-Teller effect, resulting in poor high-temperature cycling performance, and is primarily used in motorcycles and power tools. Layered lithium-rich manganese-based materials (LMR) are expected to become next-generation cathode materials for lithium-ion batteries due to their advantages such as high specific capacity and low cost. However, issues such as severe voltage decay during cycling, low rate performance, low density, and instability of the electrolyte at high voltages, which seriously affect the progress of their commercialization.

[0004] Therefore, developing an LMR material with a new, special microstructure and enhancing the solid-solution effect of the two crystalline phases in the LMR material is of great significance in achieving long cycle life, high specific capacity, and high rate performance of the battery. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a lithium-rich manganese oxide positive electrode material, a method for producing the same, a use thereof, and a positive electrode sheet and use thereof, in order to overcome the problems of the lithium-rich manganese oxide positive electrode material existing in the prior art, which has low initial coulombic efficiency, low discharge capacity, low energy efficiency, poor rate performance, and poor cycle performance, and the lithium-rich manganese metal oxide positive electrode material has high initial efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance. [Means for solving the problem]

[0006] In order to achieve the above object, a first aspect of the present invention provides a lithium-rich manganese oxide cathode material, wherein the chemical composition of the cathode material is: xLi[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2·(1-x)LiMn 1-b M′ b O2, The XRD spectrum of the positive electrode material by XRD shows a diffraction peak P within the range of diffraction angle 2θ1 [43.5(1−x)+44x]°≦2θ1≦[44(1−x)+45x]°. (1) exists, The XRD spectrum of the positive electrode material by XRD shows a diffraction peak P within the range of diffraction angle 2θ2 [17.7(1−x)+18.3x]°≦2θ2≦[19.2(1−x)+19.8x]°. (2) exists, Here, x satisfies 0.35≦x≦0.63.

[0007] A second aspect of the present invention provides a method for producing the above-mentioned lithium-rich manganese oxide positive electrode material, the method comprising: uniformly mixing a precursor containing manganese and M1, a lithium source, and an optional additive containing element M2; and performing two-stage heating and sintering of the mixed material to obtain the lithium-rich manganese oxide positive electrode material; Here, the amount of the lithium source used, the amount of the precursor used, and the amount of the additive containing the element M2 used make N(Li) / [n(Mn)+n(M1)+n(M2)] 1.28-1.5; The two-stage temperature-rise sintering includes a step of increasing the temperature from room temperature to a primary sintering temperature at a first temperature-rise rate to perform primary sintering, and then increasing the temperature to a secondary sintering temperature at a second temperature-rise rate to perform secondary sintering, where the first temperature-rise rate is equal to or greater than the second temperature-rise rate.

[0008] A third aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising a positive electrode active material, the positive electrode active material comprising a lithium-rich manganese oxide positive electrode material, a conductive agent, and a binder, the content of the lithium-rich manganese oxide positive electrode material being 90 wt % or more based on the total weight of the positive electrode active material; The lithium-rich manganese oxide positive electrode material is the lithium-rich manganese oxide positive electrode material described above.

[0009] A fourth aspect of the present invention provides use of the lithium-rich manganese oxide positive electrode material or the positive electrode sheet in a lithium ion battery.

[0010] According to the above technical solutions, the lithium-rich manganese oxide positive electrode material and its manufacturing method and use, the positive electrode sheet and its use according to the present invention can achieve the following beneficial effects:

[0011] (1) The lithium-rich manganese oxide cathode material of the present invention has a monoclinic crystal phase, Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′b The cathode material is a solid-solution composite of two crystalline phases of O2, with the two crystalline phases having a specific content ratio, and has a specific microstructure, so that the cathode material has high initial efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance.

[0012] (2) The lithium-rich manganese oxide cathode material of the present invention uses specific elements to realize localized lattice substitution in the two crystalline phases, which can adjust and modify the electronic structure of the microstructure of the two crystalline phases in the material, form vacancy defects, and strengthen the binding energy of the metal-oxygen bond, improving the transport of electrons and ions, suppressing oxygen release under high voltage, and helping to improve the reversible stability of the structure of the cathode material during electrochemical cycling, thereby improving the discharge specific capacity, energy efficiency, rate performance, and cycle performance of the cathode material. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an XRD spectrum of a positive electrode material S-1 of Example 1. [Figure 2] 1 is an XRD spectrum of a positive electrode material S-2 of Example 2. [Figure 3] 1 is an XRD spectrum of a positive electrode material S-3 of Example 3. [Figure 4] 1 is an XRD spectrum of a positive electrode material S-4 of Example 4. [Figure 5] 1 is an XRD spectrum of a positive electrode material D-2 of Comparative Example 2. [Figure 6] FIG. 1 is an SEM image of a positive electrode material S-5 of Example 5. [Figure 7] 1 is an initial charge / discharge graph of a lithium ion battery assembled from positive electrode material S-1, positive electrode material S-4, and positive electrode material D-2. [Figure 8] 1 is an initial charge / discharge graph of a lithium ion battery assembled from positive electrode material S-1, positive electrode material S-5, and positive electrode material S-6. [Figure 9]1 is an initial charge / discharge graph of a lithium-ion battery assembled from cathode material S-5 and cathode material D-3. [Figure 10] FIG. 1 is a voltage cycle diagram of a lithium-ion battery assembled from cathode material S-1 and cathode material S-5. [Figure 11] FIG. 1 is a capacity cycle diagram of a lithium-ion battery assembled from cathode material S-1 and cathode material S-5. [Figure 12] FIG. 1 is a voltage cycle diagram of a lithium-ion battery assembled from cathode material S-1 and cathode material D-2. [Figure 13] FIG. 1 is a capacity cycle diagram of a lithium-ion battery assembled from cathode material S-1 and cathode material D-2. [Figure 14] FIG. 1 is a voltage cycle diagram of a lithium-ion battery assembled from cathode material S-5 and cathode material D-3. [Figure 15] FIG. 1 is a capacity cycle diagram of a lithium-ion battery assembled from cathode material S-5 and cathode material D-3. DETAILED DESCRIPTION OF THE INVENTION

[0014] The endpoints of ranges and any value disclosed herein should be understood to be not limited to such exact ranges or values, but to include values ​​close to those ranges or values. In the case of ranges of numerical values, values ​​between the endpoints of each range, between the endpoints of each range and any single point value, and between any single point value can be combined with each other to create one or more new numerical ranges, and these numerical ranges are considered to be specifically disclosed in the specification.

[0015] A first aspect of the present invention provides a lithium-rich manganese oxide cathode material, the chemical composition of the lithium-rich manganese oxide cathode material being: xLi[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2·(1-x)LiMn 1-b M′ b O2, The XRD spectrum of the positive electrode material by XRD shows a diffraction peak P within the range of diffraction angle 2θ1 [43.5(1−x)+44x]°≦2θ1≦[44(1−x)+45x]°. (1) exists, The XRD spectrum of the positive electrode material by XRD shows a diffraction peak P within the range of diffraction angle 2θ2 [17.7(1−x)+18.3x]°≦2θ2≦[19.2(1−x)+19.8x]°. (2) exists. Here, x satisfies 0.35≦x≦0.63.

[0016] In the present invention, the lithium-rich manganese oxide positive electrode material is a monoclinic crystalline phase Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ b The cathode material is a solid-solution composite of two crystalline phases of O2, with the two crystalline phases having a specific content ratio. The cathode material also has a specific microstructure, which allows the cathode material to have high initial efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance.

[0017] Specifically, in the present invention, the diffraction peak P (1) and diffraction peak P (2) If the above conditions are satisfied, the position of Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ b The content ratio of the two crystalline phases, O2, is appropriate, the solid solution effect is good, the structure is stable, and the material has high initial efficiency, high discharge capacity, high energy efficiency, good rate performance, and excellent cycle performance.

[0018] In the present invention, the monoclinic crystalline phase Li[Li 1 / 3 (Mn 1-a Ma ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ b The content ratio (x) of the two crystalline phases, O2, is determined by quantitative calculation based on the measurement results of XRD and ICP elements.

[0019] Furthermore, [43.6(1-x)+44x]°≦2θ1≦[44(1-x)+45x]°.

[0020] Furthermore, [17.8(1-x)+18.3x]°≦2θ2≦[19.2(1-x)+19.8x]°.

[0021] Furthermore, 0.4≦x≦0.55.

[0022] According to the present invention, 0≦a≦0.1, 0.15≦b≦0.85, M is selected from at least one element of Nb, Ru, Mo, Co, Ti and Zr, and M′ is selected from at least one element of Ni, Co, Al, Zr, Nb, Ti, Sc, Y, Sn, Cr, W, Mg, Mo, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B.

[0023] In the present invention, the specific values ​​of the content ratio (x) and a and b in the chemical formula of the lithium-rich manganese oxide positive electrode material are as follows: In the manufacturing method, the ratio (x) of the two crystalline phases is determined according to the ratio of Li in the positive electrode material and the transition metal elements other than Li in the positive electrode material; if the doping elements M1 and M2 can be simultaneously doped into two crystalline phases, the doping amount is distributed according to the ratio of the two crystalline phases; if only one crystalline phase is available, all of it is doped into that crystalline phase; specifically, the specific values ​​of a and b in each crystalline phase are determined so that the doping elements replace the main transition metal elements other than Li in the crystalline phase in the ratio of the main transition metal elements in the crystalline phase.

[0024] In the present invention, the positive electrode material is a monoclinic crystalline phase Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3]O2 and hexagonal crystalline phase LiMn 1-b M′ b O2, and the inventors have researched and found that the lattice substitution of the orientation element allows the M element (e.g., Nb, Ru, Mo, Co, Ti, or Zr, etc.) to form Li[Li 1 / 3 Mn 2 / 3 ]O2 to replace the Mn position, Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2, and Mn positions in LiMnO2 are substituted with M' elements (e.g., Ni, Co, Al, Zr, Nb, Ti, Sc, Y, Sn, Cr, W, Mg, Mo, Na, La, Os, Pr, Re, Ru, Sr, Sm, or Ta, etc.), to obtain LiMn 1-b M′ b O2 component is obtained, and Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and LiMn 1-b M′ b It has been discovered that the two crystalline phase components, O2, at a specific content ratio form a uniform and stable solid solution composite structure, i.e., the lithium-rich manganese oxide cathode material of the present invention.

[0025] In the present invention, the inventors have found through their research that the lithium-rich manganese oxide cathode material of the present invention has an oriented element lattice substitution, which effectively stabilizes the crystal structure of the cathode material, improves the microzone structure of the material, and realizes the improvement of the electrochemical performance of the material. For example, Nb, Ru, Mo, Li[Li 1 / 3 Mn 2 / 3 ]O2, partial substitution at the Mn position can form Nb-O bonds, Ru-O bonds, and Mo-O bonds with stronger bond energies, which contributes to the reduction of O during the charging process. 2- It can stabilize the oxidation reaction of anions, suppress the generation and deposition of oxygen, and compensate for the charge during the discharge process, eliminating excess Mn 3+ To avoid deterioration of cycle performance due to the generation of Li, Co, Ti, Zr, 1 / 3 Mn 2 / 3Partial substitution at the Mn site in ]O2 can inhibit the migration of manganese ions and enhance the conductivity of the material, thereby improving the cycle and rate capabilities of the material. 1-b M′ b The introduction of M' elements (such as Ni, Co, Al, Zr, Nb, Ti, Sc, Y, Sn, Cr, W, Mg, Mo, La, Os, Pr, Re, Ru, Sr, Sm, Ta, and B) into O2 can adjust and modify the local electronic structure, stabilize the crystal structure of the material, and improve the initial efficiency, discharge capacity, rate capability, and cycle life of the material. Doping elements such as Ti, Zr, Nb, La, W, Co, and B can form lithium-containing compounds (e.g., LiNbO3, Li2ZrO3, or Li4Ti5O3) on the surface of the material particles or at the interface between particles. 12 or Li3BO3 or LaNiO3, etc.), which stabilizes the particle surface structure or interfacial strength between particles or the grain boundary structure between primary crystal grains of the positive electrode material, extends the cycle life of a lithium ion battery containing the positive electrode material, and accelerates the transport of lithium ions between particles and interfaces, thereby improving the rate performance and cycle performance of a lithium ion battery containing the positive electrode material.

[0026] According to the present invention, the diffraction peak P present within the diffraction angle 2θ1 range of the XRD spectrum of the positive electrode material (1) The half width of the FWHM is 0.35≦FWHM (1) ≦0.50.

[0027] In the present invention, the diffraction peak P present within the diffraction angle 2θ1 range (1) When the half-width of the peak falls within the above range, it indicates that the material has suitable crystallinity and the atoms are arranged in an orderly manner, thereby enabling it to exhibit higher capacity, better rate performance, and better cycle performance. If the half-width is too large, the crystal structure is poor, the order of the atoms is poor, and the electrochemical performance of the material is significantly worse. If the half-width is too small, the material has too good crystallinity, the size of the primary particles increases, the impedance increases, and ion diffusion is difficult, resulting in poor capacity, rate performance, and cycle performance.

[0028] Furthermore, a diffraction peak P present within the diffraction angle 2θ1 range of the XRD spectrum of the positive electrode material (1) The half width of the FWHM is 0.38≦FWHM (1) ≦0.45.

[0029] According to the present invention, the positive electrode material has a diffraction peak P within the diffraction angle 2θ2 range of the XRD spectrum by XRD. (2) FWHM (2) 0.17≦FWHM (2) ≦0.28.

[0030] Furthermore, the positive electrode material has a diffraction peak P within the diffraction angle 2θ2 range of the XRD spectrum by XRD. (2) FWHM (2) 0.18≦FWHM (2) ≦0.24.

[0031] According to the present invention, the diffraction peak P present within the diffraction angle 2θ2 range of the XRD spectrum of the positive electrode material (2) Peak area S (2) and the diffraction peak P within the diffraction angle 2θ1 range (1) Peak area S (1) teeth, 1.1≦S (2) / S (1) ≦1.8.

[0032] In the present invention, the diffraction peak P (2) Peak area S (2) and diffraction peak P (1) Peak area S (1) When the ratio of satisfies the above range, the material has a better solid solution degree of the two crystalline phases, a better content ratio of the two crystalline phases, and good crystallinity, thereby exhibiting good electrochemical performance.

[0033] Furthermore, 1.2≦S (2) / S (1) ≦1.7.

[0034] In the present invention, the full width at half maximum (FWHM) and peak area (S) of the diffraction peak are measured by XRD and are obtained by reading the data using Rigaku Integral Int. Calculation software.

[0035] According to the present invention, the compacted density of the positive electrode material is ≥ 2.2 g / cm 3 , preferably ≥ 2.5 g / cm 3 , more preferably ≥ 2.8 g / cm 3 is.

[0036] According to the present invention, the specific surface area SSA of the positive electrode material is 0.3 m 2 / g≦SSA≦3m 2 / g, preferably 0.5m 2 / g≦SSA≦2.5.

[0037] According to the present invention, the surface Li2CO3 content of the positive electrode material is not more than 2700 ppm, preferably not more than 2400 ppm, more preferably not more than 2000 ppm, and the surface LiOH content of the positive electrode material is not more than 1600 ppm, preferably not more than 1400 ppm, more preferably not more than 1200 ppm.

[0038] A second aspect of the present invention provides a method for producing the above-mentioned lithium-rich manganese oxide positive electrode material, the method comprising: The method comprises the steps of: uniformly mixing a precursor containing manganese and M1, a lithium source, and an optional additive containing element M2; and then subjecting the mixed material to two-stage heating and sintering to obtain the lithium-rich manganese oxide positive electrode material; Here, the amount of the lithium source used, the amount of the precursor used, and the amount of the additive containing element M2 used make n(Li) / [n(Mn)+n(M1)+n(M2)] 1.28-1.5; The two-stage temperature-rise sintering includes a step of raising the temperature from room temperature to a primary sintering temperature at a first heating rate to perform the primary sintering, and a step of raising the temperature to a secondary sintering temperature at a second heating rate to perform the secondary sintering, wherein the first heating rate is equal to or greater than the second heating rate.

[0039] In the present invention, the monoclinic crystalline phase Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ b M and M′ in O2 originate from the M1 element in the precursor and the additive containing element M2.

[0040] In the present invention, the inventor has conducted research and found that by adjusting and controlling the lithium compounding ratio (n(Li) / [n(Mn)+n(M1)+n(M2)]) and sintering precision in the manufacturing method, it is possible to obtain a monoclinic crystalline phase, Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ b A cathode material consisting of a solid solution composite of two crystalline phases, xLi[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2·(1-x)LiMn 1-b M′ b It has been discovered that by obtaining O2 and controlling the contents of the two crystalline phases to an appropriate ratio, the resulting positive electrode material has excellent overall performance, such as high initial coulombic efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance. If the lithium content does not meet the range specified in the present invention, the two crystalline phases in the positive electrode material cannot form a stable solid solution structure, resulting in crystalline phase separation, which will significantly reduce the initial coulombic efficiency, discharge capacity, energy efficiency, rate performance, and cycle performance of lithium-ion batteries containing the positive electrode material.

[0041] In the present invention, the inventor has found through research that by sintering using the above-mentioned specific sintering step, a monoclinic crystalline phase Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ bA cathode material consisting of a solid solution composite of two crystalline phases, xLi[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2·(1-x)LiMn 1-b M′ b By obtaining O2 and controlling the contents of the two crystalline phases in an appropriate ratio, the resulting positive electrode material has excellent overall performance, such as high initial coulombic efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance.

[0042] Furthermore, the amount of the lithium source used, the amount of the precursor used, and the amount of the additive containing element M2 used make N(Li) / [n(Mn)+n(M1)+n(M2)] 1.28-1.5, preferably 1.3-1.45.

[0043] According to the present invention, M1 and M2 may be the same or different and are each independently selected from at least one element of Ni, Co, Al, Zr, Nb, Ti, Sc, Y, Sn, Cr, W, Mg, Mo, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B.

[0044] In the present invention, when the mixed material is sintered, some elements among M1 and M2 elements can realize the lattice substitution of the orienting element, for example, Nb, Ru, Mo, Co, Ti or Zr, and Li[Li 1 / 3 (Mn 1-a M a ) 2 / 3 ]O2 and hexagonal crystalline phase LiMn 1-b M′ b O2 can be orientationally doped, and other elements in M1 and M2 elements other than Nb, Ru, Mo, Co, Ti or Zr are added to form the hexagonal crystal phase LiMn 1-b M′ b Only the O2 structure could be doped to obtain the lithium-rich manganese oxide cathode material described in the present invention.

[0045] In the present invention, the type of additive containing element M2 is not particularly limited as long as it can provide element M2, and is, for example, at least one of oxides, hydroxides, oxyhydroxides, phosphates, fluorides, borides, and carbonates containing element M2.

[0046] According to the present invention, the amount of the additive containing element M2 and the amount of the precursor used make n(M2) / [n(Mn)+n(M1)+n(M2)] 0-0.1.

[0047] In the present invention, when the amount of the additive containing element M2 used is controlled to satisfy the above range, the element can be doped as much as possible into the interior of the crystal lattice, and the doping is uniform, avoiding residue on the surface of the material or local enrichment, and the material exhibits higher capacity and better cycle performance.

[0048] Furthermore, the amount of the additive containing element M2 used and the amount of the precursor used make n(M2) / [n(Mn)+n(M1)+n(M2)] 0.001-0.05.

[0049] In the present invention, the M1 element in the precursor is introduced by adding a compound containing the M1 element, such as sulfate, chloride, nitrate, acetate, citrate, carbonate, phosphate, oxalate, or fluoride, during precursor coprecipitation.

[0050] According to the present invention, the chemical formula of the precursor is Mn v M 1γ (OH) 2±δ or Mn v M 1γ CO3, where 0.4≦v≦0.8, 0.2≦γ≦0.6, and 0≦δ≦0.1.

[0051] In the present invention, the method for producing the precursor is not particularly limited, and the precursor can be produced using a conventional method in this field.

[0052] In the present invention, the lithium source is not particularly limited, and at least one of conventional lithium sources in this field, such as lithium hydroxide, lithium carbonate, and lithium nitrate, can be used.

[0053] According to the present invention, in the process of the two-stage temperature-rising sintering, the secondary sintering temperature is controlled to 800 to 1050° C., and the two-stage temperature-rising sintering is carried out in an oxygen-containing atmosphere.

[0054] Furthermore, the two-stage temperature-rising sintering includes a step of raising the temperature from room temperature to a primary sintering temperature at a first temperature-rising rate of 5°C / min or more to perform primary sintering, and then raising the temperature to a secondary sintering temperature at a second temperature-rising rate of 5°C / min or less to perform secondary sintering, and the secondary sintering temperature is 800 to 1050°C.

[0055] In the present invention, furthermore, when the first heating rate and the second heating rate are controlled to satisfy the above ranges, the crystallinity and primary particle size of the positive electrode material according to the present invention are appropriate, which is helpful for the orderly arrangement of atoms and for uniform lithiation during the reaction process, thereby avoiding lithium enrichment on the outside and lithium deficiency on the inside of the material, and enhancing the degree and effect of solid solution of the two crystalline phases, so that the prepared positive electrode material has excellent overall performance, for example, high initial coulombic efficiency, high discharge capacity, high energy efficiency, high rate performance, and high cycle performance.

[0056] Furthermore, the first heating rate is 5°C / min to 10°C / min, and the second heating rate is 1°C / min to 4°C / min.

[0057] According to the present invention, the primary sintering temperature is 300 to 600° C., and the primary sintering time is 2 to 6 hours.

[0058] Furthermore, the primary sintering temperature is 400 to 550°C, and the primary sintering time is 3 to 5 hours.

[0059] According to the present invention, the secondary sintering temperature is 800 to 1050°C, and the secondary sintering time is 6 to 15 hours.

[0060] Furthermore, the secondary sintering temperature is 800 to 950°C, and the secondary sintering time is 6 to 12 hours.

[0061] According to the invention, the sintering is carried out in an oxygen-containing atmosphere.

[0062] In the present invention, the oxygen-containing atmosphere is selected from one of air, a mixed gas of oxygen and air, and a mixed gas of air and carbon dioxide.

[0063] In a more preferred embodiment of the present invention, when the lithium ratio (n(Li) / [n(Mn)+n(M1)+n(M2)]), the sintering step, and the types of M1 and M2 simultaneously meet the requirements of the present invention, the overall performance of the positive electrode material produced thereby can be further improved.

[0064] A third aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising a positive electrode active material, the positive electrode active material comprising a lithium-rich manganese oxide positive electrode material, a conductive agent, and a binder, the content of the lithium-rich manganese oxide positive electrode material being 90 wt % or more based on the total weight of the positive electrode active material; Here, the lithium-rich manganese oxide positive electrode material is the lithium-rich manganese oxide positive electrode material described above.

[0065] A fourth aspect of the present invention provides use of the lithium-rich manganese oxide positive electrode material or the positive electrode sheet in a lithium ion battery.

[0066] The present invention will be described in detail below with reference to examples.

[0067] In the following examples and comparative examples, Unless otherwise stated, all ingredients are commercially available. Unless otherwise specified, all percentages and usage ratios are molar ratios.

[0068] In the following examples, the relevant performance is obtained by the following method: (1) XRD material phase test: Tested using a SmartLab 9kW model X-ray diffractometer manufactured by Rigaku Co., Ltd. (X-ray wavelength: 0.154 nm), the scanning ranges were 17-22° and 42-47°, respectively, the step size was 0.02°, and the scanning speed was 1° / min. (2) Specific surface area: Obtained by testing with a Tristar II3020 model specific surface tester from Micromertics, USA. (3) Compaction density: Obtained by testing with a powder impedance tester, model MCP-PD51, manufactured by Mitsubishi Chemical Corporation of Japan, with a test pressure of 20KN. (4) Surface residual alkali test: Obtained by titration using a Swiss-based intelligent potential titrator, titrated with 0.1 mol / L standard hydrochloric acid solution, (5) Morphological test: Obtained by testing with a scanning electron microscope of Hitachi HITACHI, Japan, model S-4800. (6) Electrochemical performance test: The electrochemical performance of the manufactured lithium-rich manganese oxide cathode material was obtained by testing a 2025-type Buckle battery in the Xinwei battery test system. Specifically, 1) The manufacturing process of 2025 type buckle battery includes the following steps: Electrode sheet preparation: The lithium-rich manganese oxide cathode material, conductive carbon black, and binder polyvinylidene fluoride were thoroughly mixed with an appropriate amount of N-methylpyrrolidone in a mass ratio of 95:3:2 to form a uniform slurry, which was then coated onto aluminum foil, dried at 120°C, roll-pressed, and punched to prepare a cathode sheet with a diameter of 11 mm. Battery assembly: The negative electrode is a Li metal sheet with a diameter of 17 mm and a thickness of 1 mm, the separator is a 25 μm thick polyethylene porous film, and the electrolyte is a mixture of 1 mol / L LiPF6, equal parts ethylene carbonate (EC), and diethyl carbonate (DEC). The positive electrode sheet, separator, negative electrode sheet and electrolyte are assembled into a 2025-type buckle battery in an Ar gas glove box in which both the water content and the oxygen content are less than 5 ppm, and the battery at this stage is designated as an inactivated battery. 2) Electrochemical performance test: Buckle battery test conditions: After fabrication, the buckle battery was left for 2 hours. After the open-circuit voltage stabilized, it was charged to a cutoff voltage of 4.6 V at a current density of 0.1 C, followed by a 30-minute constant-voltage charge at 0.02 C. It was then discharged at the same current density to a cutoff voltage of 2 V. This cycle was repeated once, and the battery at this point was designated as an activated battery. The activated battery was then subjected to a charge-discharge test at 0.1 C between 2 and 4.6 V at 25°C and a charge-discharge interval of 2 to 4.6 V. The charge-discharge capacity of the material was evaluated. The activated battery was then subjected to charge-discharge tests at 0.1 C, 0.2 C, 0.33 C, 0.5 C, and 1 C. The rate performance of the material was evaluated by the ratio of the 1 C capacity to the 0.1 C capacity. The cycle performance of the material was evaluated by 80 cycles at 1 C between 2 and 4.6 V.

[0069] The following preparation examples are provided to illustrate the preparation of precursors containing manganese and M1 according to the present invention.

[0070] Manufacturing Example 1 Manganese sulfate and nickel sulfate (Mn:Ni) were dissolved in a 2:1 molar ratio to obtain a sulfate solution. Sodium hydroxide was dissolved to obtain a 6 mol / L alkaline solution, and ammonia water was dissolved to obtain a 5 mol / L complexing agent solution. The sulfate solution, alkaline solution, and complexing agent solution were then added to a 20L reactor in parallel and reacted. The stirring speed was maintained at 600 rpm, the mixed salt solution flow rate was 300 mL / h, the reaction pH was 11.6, the reaction temperature was 40°C, and the ammonia concentration in the reaction system was 2 g / L. The entire reaction was carried out under N2 gas. The reaction was allowed to stand for 60 hours. The resulting slurry was then solid-liquid separated and washed. It was then dried at 105°C for 10 hours and sieved to obtain a Mn-containing solution. 0.667 Ni 0.333 A precursor material, (OH)2, is obtained and designated as P-1.

[0071] Manufacturing Example 2 The precursor was prepared by the method of Preparation Example 1, except that the ratio of manganese sulfate to nickel sulfate was different. Specifically, manganese sulfate and nickel sulfate were dissolved in a molar ratio of Mn to Ni of 3:2 to obtain a sulfate solution. 0.6 Ni 0.4 A precursor material, (OH)2, is obtained and designated as P-2.

[0072] Manufacturing Example 3 The precursor was prepared by the method of Preparation Example 1, except that the ratio of manganese sulfate to nickel sulfate was different. Specifically, manganese sulfate and nickel sulfate were dissolved in a molar ratio of Mn to Ni of 3:1 to obtain a sulfate solution. 0.75 Ni 0.25 A precursor material, (OH)2, is obtained and designated as P-3.

[0073] The following examples are intended to illustrate the lithium-rich manganese oxide cathode materials prepared in accordance with the present invention.

[0074] Example 1 Precursor P-1, lithium hydroxide, additives Al2O3 and Co(OH)2 were uniformly mixed in a high mixer with n(Li):[n(Ni)+n(Mn)+n(Al)+n(Co)]=1.4, n(Al):[n(Ni)+n(Mn)+n(Al)+n(Co)]=0.002, and n(Co):[n(Ni)+n(Mn)+n(Al)+n(Co)]=0.002. The mixture was heated from room temperature to 400°C at a first heating rate of 5°C / min in an air atmosphere, maintained at this temperature for 5 hours, heated to 900°C at a second heating rate of 3°C / min, maintained at this temperature for 10 hours, and then cooled naturally to obtain cathode material S-1.

[0075] Here, the chemical formula of the positive electrode material S-1 is: 0.5Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.5LiMn 0.4423 Ni 0.5529 Al 0.0032 Co 0.0016 It is O2.

[0076] Example 2 The method is similar to that of Example 1, except that the amount of lithium salt added is different, specifically: n(Li):[n(Ni)+n(Mn)+n(Al)+n(Co)]=1.3. Positive electrode material S-2 was obtained. Here, the chemical formula of the positive electrode material S-2 is: 0.391Li[Li 1 / 3 (Mn 0.99745 Co 0.00255 ) 2 / 3 ]O2·0.609LiMn 0.5214 Ni 0.4740 Al 0.0029 Co 0.0017 It is O2.

[0077] Example 3 The method is similar to that of Example 1, except that the amount of lithium salt added is different, specifically: n(Li):[n(Ni)+n(Mn)+n(Al)+n(Co)]=1.45, and positive electrode material S-3 was obtained. Here, the chemical formula of the positive electrode material S-3 is: 0.551Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.449LiMn 0.3919 Ni 0.6029 Al 0.0036 Co 0.0016 It is O2.

[0078] Example 4 Using a method similar to that of Example 1, the difference was the amount of lithium salt added, specifically, n(Li):[n(Ni)+n(Mn)+n(Al)+n(Co)]=1.5. Positive electrode material S-4 was obtained. The chemical formula of the positive electrode material S-4 is: 0.6Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.4LiMn 0.3314 Ni 0.6630 Al 0.004 Co 0.0016 It is O2.

[0079] Example 5 Using a method similar to that of Example 1, the precursor P-1, lithium hydroxide, and additive Co(OH)2 were uniformly mixed in a high mixer with n(Li):[n(Ni)+n(Mn)+n(Co)]=1.40 and n(Co):[n(Ni)+n(Mn)+n(Co)]=0.002 to obtain cathode material S-5. Here, the chemical formula of the positive electrode material S-5 is: 0.5Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.5LiMn 0.4437 Ni 0.5547 Co 0.0016 It is O2. The SEM image of the positive electrode material S-5 is shown in FIG. 6, and as can be seen from FIG. 6, the positive electrode material is in the form of near-spherical particles.

[0080] Example 6 Using a method similar to that of Example 1, except that precursor P-1, lithium hydroxide, and additive Al2O3 were uniformly mixed in a high-mixer with n(Li):[n(Ni)+n(Mn)+n(Al)]=1.40 and n(Al):[n(Ni)+n(Mn)+n(Al)]=0.002, positive electrode material S-6 was obtained. Here, the chemical formula of the positive electrode material S-6 is: 0.5Li[Li 1 / 3 (Mn1) 2 / 3 ]O2·0.5LiMn 0.4429 Ni 0.5538 Al 0.0033 It is O2.

[0081] Example 7 The same synthesis method and conditions as in Example 1 were used, except that precursor P-1 and lithium hydroxide were uniformly mixed in a high mixer at n(Li):[n(Ni)+n(Mn)]=1.40 to obtain cathode material S-7, whose chemical formula is: 0.5Li[Li 1 / 3 (Mn1) 2 / 3 ]O2·0.5LiMn0.4444 Ni 0.5556 It is O2.

[0082] Example 8 Precursor P-2, lithium hydroxide, and additives tungsten oxide and titanium dioxide were uniformly mixed in a high-mixer at n(Li):[n(Mn)+n(Ni)+n(W)+n(Ti)]=1.35, n(W):[n(Mn)+n(Ni)+n(W)+n(Ti)]=0.002, and n(Ti):[n(Mn)+n(Ni)+n(W)+n(Ti)]=0.005. The mixture was heated from room temperature to 600°C at a first heating rate of 8°C / min in an oxygen atmosphere, maintained at this temperature for 5 hours, heated to 850°C at a second heating rate of 3°C / min, maintained at this temperature for 10 hours, and then allowed to cool naturally to obtain cathode material S-8. Here, the chemical formula of the positive electrode material S-8 is: 0.447Li[Li 1 / 3 (Mn 0.99355 Ti 0.00645 ) 2 / 3 ]O2·0.553LiMn 0.3818 Ni 0.6108 Ti 0.0043 W 0.0031 It is O2.

[0083] Example 9 Precursor P-3, lithium hydroxide, and additives molybdenum oxide and cobalt oxide were uniformly mixed in a high-mixer with n(Li):[n(Mn)+n(Ni)+n(Co)+n(Mo)]=1.38, n(Mo):[n(Mn)+n(Ni)+n(Co)+n(Mo)]=0.02, and n(Co):[n(Mn)+n(Ni)+n(Co)+n(Mo)]=0.05. The mixture was heated from room temperature to 500°C at a first heating rate of 10°C / min in an air atmosphere, maintained at this temperature for 4 hours, and then heated to 1000°C at a second heating rate of 4°C / min and maintained at this temperature for 10 hours to obtain cathode material S-9. Here, the chemical formula of the positive electrode material S-9 is 0.479Li[Li 1 / 3 (Mn 0.9118 Co 0.063 Mo 0.0252 ) 2 / 3 ]O2·0.521LiMn 0.5617 Ni 0.3795 Co0.042 Mo 0.0168 It is O2.

[0084] Comparative Example 1 The method is similar to that of Example 1, except that the amount of lithium salt added is different, specifically: n(Li):[n(Ni)+n(Mn)+n(Al)+n(Co)]=1.55. Positive electrode material D-1 was obtained, and the chemical formula of the positive electrode material was: 0.647Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.353LiMn 0.2577 Ni 0.7362 Al 0.0044 Co 0.0016 It is O2.

[0085] Comparative Example 2 Using a method similar to that of Example 1, the difference is that the amount of lithium salt added is different, specifically, n(Li):[n(Ni)+n(Mn)+n(Al)+n(Co)]=1.25. Positive electrode material D-2 is obtained, and the chemical formula of the positive electrode material is: 0.333Li[Li 1 / 3 (Mn 0.9973 Co 0.0027 ) 2 / 3 ]O2·0.667LiMn 0.5531 Ni 0.4424 Al 0.0027 Co 0.0018 It is O2.

[0086] Comparative Example 3 Using the same method as in Example 5, except that the temperature was directly increased to 900°C at 5°C / min and kept at that temperature for 10 hours, cathode material D-3 was obtained. The chemical formula of the cathode material was: 0.5Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.5LiMn 0.4437 Ni 0.5547 Co 0.0016 It is O2.

[0087] Comparative Example 4 The same method as in Example 5 was used, except that the temperature was increased from room temperature to 400°C at a first heating rate of 3°C / min, and then maintained at that temperature for 5 hours. The temperature was then increased to 900°C at a second heating rate of 10°C / min, and then maintained at that temperature for 10 hours. This gave a cathode material D-4, whose chemical formula is: 0.5Li[Li 1 / 3 (Mn 0.9976 Co 0.0024 ) 2 / 3 ]O2·0.5LiMn 0.4437 Ni 0.5547 Co 0.0016 It is O2.

[0088] The XRD spectra of the positive electrode materials S-1 to S-4 of Examples 1 to 4 and the positive electrode material D-2 of Comparative Example 2 are shown in Figures 1 to 5, respectively. As can be seen from Figures 1 to 5, the proportions of the two crystalline phases in the positive electrode materials according to the present invention and the solid solubility of the two crystalline phases are good. Specifically, the XRD P (1) The peak is a single peak with good symmetry, whereas the peak in the XRD diagram of the positive electrode material of Comparative Example 2 is split, the ratio of the two crystalline phases is inappropriate, and the solid solubility of the two crystalline phases is poor.

[0089] Test Example 1 The structure and performance of the lithium-rich manganese oxide positive electrode materials prepared in Examples 1 to 9 and Comparative Examples 1 to 4 were tested, and the results are shown in Table 1.

[0090] [Table 1]

[0091] As can be seen from the results in Table 1, compared with Comparative Examples 1 to 4, P of Examples 1 to 9 employing the present invention is (1) , P (2) , FWHM (1) , FWHM (2) and S (2) / S (1) All of these are within the required range of the present invention and therefore have good electrochemical performance.

[0092] Test Example 2 The lithium-rich manganese oxide positive electrode materials prepared in Examples 1 to 9 and Comparative Examples 1 to 4 were used as positive electrode sheets for lithium ion batteries to obtain lithium ion batteries. The performance of the lithium ion batteries was tested, and the results are shown in Table 2.

[0093] [Table 2]

[0094] As can be seen from Table 2, by comparing Examples 1, 2, 3, and 4, it is possible to adjust and control the capacity, energy efficiency, rate performance, and cycle performance of the positive electrode material. Optimal performance is achieved when n(Li):[n(Ni) + n(Mn) + n(Al) + n(Co)] = 1.4. By comparing Example 1 and Example 5, it is found that doping Al into the hexagonal crystalline phase can significantly improve the discharge capacity and cycle performance of the material. By comparing Example 1 and Example 6, it is found that doping Co into the monoclinic crystalline phase and the hexagonal crystalline phase can significantly improve the discharge capacity, rate performance, and cycle performance of the material. By comparing Example 1 and Example 7, it is found that doping Co into the monoclinic crystalline phase and doping Co and Al into the hexagonal crystalline phase plays an important role in improving the discharge capacity, rate performance, and cycle performance of the material. By comparing Examples 1 to 4 and Comparative Examples 1 and 2, it is found that the content ratio of the two crystalline phases has a significant impact on the capacity, rate, and cycle of the material, and that performance is significantly improved within the range provided by the present invention. By comparing Example 5 with Comparative Examples 3 and 4, it can be seen that the two-stage sintering accuracy and the appropriate heating rate can improve the capacity, rate and cycle performance of the material.

[0095] The initial charge / discharge curves of Example 1, Example 4, and Comparative Example 2 are shown in FIG. 7. As can be seen from FIG. 7, the discharge capacities of the lithium ion batteries assembled from the positive electrode materials of Example 1 and Example 4 are significantly higher than that of Comparative Example 2, indicating that the appropriate content ratio of the two crystalline phases and the degree of solid solution of the two crystalline phases are very important to the performance of the material; otherwise, very low capacity will be exhibited.

[0096] The initial charge / discharge curves for Examples 1, 5, and 6 are shown in Figure 8. As can be seen from Figure 8, compared to Example 5, after doping Al into the hexagonal crystalline phase in Example 1, the discharge capacity did not decrease, but the charge / discharge voltage difference decreased, indicating a decrease in the polarization of the material and improved kinetics. Compared to Example 6, doping Co crystal lattice into the monoclinic and hexagonal crystalline phases in Example 1 further increased the discharge capacity and improved the reaction kinetics of the material.

[0097] The initial charge-discharge curves of Example 5 and Comparative Example 3 are shown in FIG. 9. As can be seen from FIG. 9, the discharge capacity of the material can be significantly improved by controlling the two-stage temperature rise and reaction rate.

[0098] Figure 10 shows the voltage cycle diagram of the lithium-ion batteries assembled from cathode materials S-1 and S-5. As can be seen from Figure 10, the voltage retention rate of the cathode materials can be effectively improved by doping Al into the hexagonal crystalline phase.

[0099] Figure 11 shows the capacity cycle diagram of the lithium-ion battery assembled from cathode material S-1 and cathode material S-5. As can be seen from Figure 11, by doping and increasing Al into the hexagonal crystalline phase, the capacity retention rate of the cathode material can be effectively improved.

[0100] Figure 12 shows the voltage cycle diagram of a lithium-ion battery assembled from cathode material S-1 and cathode material D-2. As can be seen from Figure 12, the voltage retention rate of the cathode material can be effectively improved by adjusting and controlling the ratio of the two crystalline phases and the degree of solid solution of the two crystalline phases.

[0101] Figure 13 shows the capacity cycle diagram of a lithium-ion battery assembled from cathode material S-1 and cathode material D-2. As can be seen from Figure 13, the capacity retention rate of the cathode material can be effectively improved by adjusting and controlling the ratio of the two crystalline phases and the degree of solid solution of the two crystalline phases.

[0102] Figure 14 shows the voltage cycle diagram of the lithium-ion battery assembled from cathode material S-5 and cathode material D-3. As can be seen from Figure 14, the voltage retention rate of the cathode material can be effectively improved by controlling the two-stage temperature increase and reaction rate.

[0103] Figure 15 shows the capacity cycle diagram of a lithium-ion battery assembled from cathode material S-5 and cathode material D-3. As can be seen from Figure 15, the capacity retention rate of the cathode material can be effectively improved by controlling the two-stage temperature increase and reaction rate.

[0104] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made on the technical solutions of the present invention, including the combination of various technical features in other suitable ways, and these simple modifications and combinations are also considered as the contents disclosed in the present invention and belong to the protection scope of the present invention.

Claims

1. A lithium-rich manganese oxide positive electrode material, the chemical formula of which is: xLi[ii １／３ (7n １－ａ 7. ａ ) ) ２／３ )) ２ ・(1-1)iｭn １－ｂ 7′ ｂ 9 ２ であり、 The XRD spectrum of the positive electrode material is measured at a diffraction angle 2θ １ is [43.5(1-x)+44x]°≦2θ １ Diffraction peak P within the range of ≦[44(1−x)+45x]° （１） exists, The XRD spectrum of the positive electrode material is measured at a diffraction angle 2θ ２ is [17.7(1-x)+18.3x]°≦2θ ２ Diffraction peak P within the range of ≦[19.2(1−x)+19.8x]° （２） exists, wherein x satisfies 0.35≦x≦0.63, 0≦a≦0.1, 0.15≦b≦0.85, M is selected from at least one element of Nb, Ru, Mo, Co, Ti and Zr, and M′ is selected from at least one element of Ni, Co, Al, Zr, Nb, Ti, Sc, Y, Sn, Cr, W, Mg, Mo, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B; A lithium-rich manganese oxide positive electrode material, characterized in that the half-width of a diffraction peak P (1) present within a diffraction angle 2θ 1 range in an XRD spectrum of the positive electrode material satisfies 0.35≦FWHM (1) ≦0.

50.

2. [43.6(1-x)+44x]°≦2θ １ 2. The lithium-rich manganese oxide positive electrode material according to claim 1, wherein the θ is ≦[44(1−x)+45x]°.

3. Diffraction angle 2θ of the XRD spectrum of the positive electrode material １ Diffraction peaks P present in the range （１） The half width of the （１） 2. The lithium-rich manganese oxide positive electrode material according to claim 1, wherein the .lambda.R.sub.2 is 0.45 or less.

4. The diffraction angle 2θ of the positive electrode material by XRD ２ Diffraction peaks P present in the range （２） Peak area S （２） and the diffraction angle 2θ １ Diffraction peaks P present in the range （１） Peak area S （１） teeth, 1.1≦S （２） / S （１） 2. The lithium-rich manganese oxide positive electrode material according to claim 1, wherein the .alpha.-z value satisfies .ltoreq.1.

8.

5. The compacted density of the positive electrode material is ≧2.2 g / cm ３ 2. The lithium-rich manganese oxide positive electrode material according to claim 1, wherein

6. A method for producing a lithium-rich manganese oxide positive electrode material according to any one of claims 1 to 5, comprising: Manganese and M １ a precursor comprising a lithium source and an optional element M ２ The method includes the steps of uniformly mixing the additives contained therein, and then subjecting the mixed material to two-stage heating and sintering to obtain the lithium-rich manganese oxide positive electrode material; Here, the amount of the lithium source used, the amount of the precursor used, and the element M ２ Depending on the amount of additive used, n(Li) / [n(Mn)+n(M １ ) + n(M ２ ) )] is 1.28-1.5, M 1 and M 2 may be the same or different and are each independently selected from at least one element of Ni, Co, Al, Zr, Nb, Ti, Sc, Y, Sn, Cr, W, Mg, Mo, Na, La, Os, Pr, Re, Ru, Sr, Sm, Ta and B, and n is the number of moles of the element in parentheses; The two-stage temperature-rise sintering includes a step of raising the temperature from room temperature to a primary sintering temperature at a first heating rate to perform primary sintering, and a step of raising the temperature to a secondary sintering temperature at a second heating rate to perform secondary sintering, wherein the first heating rate is equal to or greater than the second heating rate.

7. The amount of the lithium source used, the amount of the precursor used, and the element M ２ Depending on the amount of additive used, n(Li) / [n(Mn)+n(M １ ) + n(M ２ ) )] is 1.3 to 1.

45.

8. The method according to claim 6, wherein the two-stage temperature-rising sintering is carried out in an oxygen-containing atmosphere.

9. A positive electrode sheet, the positive electrode sheet comprising a positive electrode active material, the positive electrode active material comprising a lithium-rich manganese oxide positive electrode material, a conductive agent, and a binder, the content of the lithium-rich manganese oxide positive electrode material being 90 wt % or more based on the total weight of the positive electrode active material; The positive electrode sheet is characterized in that the lithium-rich manganese oxide positive electrode material is the lithium-rich manganese oxide positive electrode material according to claim 1.

10. Use of the lithium-rich manganese oxide positive electrode material according to any one of claims 1 to 5 or the positive electrode sheet according to claim 9 in a lithium ion battery.

Images