A positive electrode material, a preparation method thereof, and a lithium ion battery

Abstract

This application provides a cathode material, its preparation method, and a lithium-ion battery, specifically a manganese-based cathode material exhibiting high initial coulombic efficiency and high cycle stability. The general molecular formula of this cathode material is: aNa. α Ni λ Mn σ M 1‑λ‑σ O 2‑γ D γ ·(1-a)Li 1+β Ni λ Mn σ M 1‑λ‑σ O 2+β‑δ D δ ; 0.05≤a≤0.20, 0.60≤α≤0.95, 0<γ≤0.20, 0.04<β<0.10, 0<δ≤0.21, and 0.9≤(λ+σ)≤1.0; M is the first dopant element, selected from at least one of Te, Ti, Mo, W, Nb, Ta, V, Sb, Sn, Si, Zr, Cr, Al, Co, Ce, Fe, Cu, La, Y, Sr, Mg, Li, and K; D is the second dopant element, selected from at least one of F, S, P, N, and B.

Description

Technical Field

[0001] This invention relates to the field of secondary energy storage battery technology, and in particular to a positive electrode material and its preparation method, and a lithium-ion battery. Background Technology

[0002] With the development of new energy technologies, higher performance requirements have been placed on lithium-ion batteries and the cathode materials that provide the main active substances for lithium-ion batteries. Among them, manganese-based lithium-rich cathode materials have high discharge specific capacity (>1000Wh / Kg), but they suffer from low initial coulombic efficiency and low cycle stability.

[0003] To improve the initial coulombic efficiency and cycle stability of lithium-rich manganese-based cathode materials, modification is often achieved by constructing composite structures coated with oxides. For example, constructing spinel phases and / or thin-layer salt phases on the surface of lithium-rich manganese-based cathode materials can effectively resist electrolyte erosion and stabilize the material surface structure, thereby improving cycle stability. However, the initial coulombic efficiency of such materials still needs improvement, and the preparation process requires an acid / alkali atmosphere, which is environmentally unfriendly; furthermore, the production efficiency is low, and the equipment requirements are high, thus hindering widespread adoption. Another example is the construction of fast ion conductors (such as Li) on the surface of lithium-rich manganese-based cathode materials. 1.4 Al 0.4 Ti 0.6 (PO4)3, Li7La3Zr2O 12 Li4Mn5O 12 Li4Ti5O 12 While cathode materials coated with fast-ion conductors (such as Li₂SnO₃, Li₂SiO₃, Li₂ZrO₃, and Li₃PO₄) exhibit improved initial coulombic efficiency and cycle stability, their performance is difficult to guarantee during mass production due to stringent requirements for preparation conditions and environment. Therefore, the current technology lacks a manganese-based cathode material with both high initial coulombic efficiency and high cycle stability. Summary of the Invention

[0004] This application provides a cathode material and its preparation method, as well as a lithium-ion battery, to provide a manganese-based cathode material with high initial coulombic efficiency and high cycle stability.

[0005] In a first aspect, embodiments of this application provide a cathode material, the general molecular formula of which is: aNa α Ni λ Mn σ M 1-λ-σ O 2-γ D γ ·(1-a)Li 1+βNi λ Mn σ M 1-λ-σ O 2+β-δ D δ ;0.05≤a≤0.20, 0.60≤α≤0.95, 0<γ≤0.20, 0.04<β<0.10, 0<δ≤0.21, And 0.9≤(λ+σ)≤1.0; M is the first doping element, and M is selected from at least one of Te, Ti, Mo, W, Nb, Ta, V, Sb, Sn, Si, Zr, Cr, Al, Co, Ce, Fe, Cu, La, Y, Sr, Mg, Li, and K; D is the second doping element, and D is selected from at least one of F, S, P, N, and B.

[0006] The cathode material provided in this application reduces material costs through cobalt-free technology. Furthermore, by ensuring that the nickel content in the binary main transition metal (nickel-manganese) is higher than 0.40, the kinetic performance of the cathode material is effectively improved, thereby increasing the initial coulombic efficiency and promoting capacity utilization. This results in a significant improvement in both its mass energy density and cycle stability (not less than 85%). Based on this, the low lithium content achieves a mass energy density not lower than, and even better than, that of existing lithium-rich cathode materials, while maintaining a lower cost.

[0007] In one possible implementation, the cathode material is a P2-O3 composite phase material; the X-ray diffraction pattern of the cathode material includes: (002) crystal plane diffraction peaks with diffraction angles of 15.5°-16.1° corresponding to the P2 phase, and (003) crystal plane diffraction peaks with diffraction angles of 18.5°-19.0° corresponding to the O3 phase, wherein the peak intensity ratio of the (002) crystal plane diffraction peaks to the peak intensity ratio of the (003) crystal plane diffraction peaks is 0.01-0.70.

[0008] One possible implementation method,

[0009] One possible implementation is 0.08≤a≤0.12, 0.8≤α≤0.95.

[0010] Secondly, embodiments of this application provide a method for preparing the cathode material as described in the first aspect and any possible implementation, comprising:

[0011] The target cathode material is obtained by N-segment sintering a mixture of sodium source, lithium source, doped source, and nickel and manganese source; wherein the nickel and manganese source is a mixture of nickel source and manganese source, and / or a source containing nickel and manganese, N is a positive integer, and the sintering temperature of the N-segment sintering is not higher than 970℃.

[0012] In one possible implementation, the N-segment sintering includes a first sintering and a second sintering, wherein the sintering temperature of the first sintering is 400-600℃ and the sintering temperature of the second sintering is 850-970℃.

[0013] In one possible implementation, the heating rate of the first sintering is 2-10℃ / min, and the holding time is 2-6 hours; the heating rate of the second sintering is 2-10℃ / min, and the holding time is 10-20 hours.

[0014] In one possible implementation, the sodium source is selected from at least one of Na₂CO₃, NaOH, NaNO₃, Na₂S, and NaCl; the lithium source is selected from LiCO₃, LiOH, and LiCl; the nickel source includes NiO; the Mn source includes Mn₂O₃; the doping source includes a first doping source corresponding to a first doping element, and / or a second doping source corresponding to a second doping element; the nickel-manganese-containing source is selected from Ni θ Mn ρ (OH)2 and / or Ni θ Mn ρ CO3; among which,

[0015] In one possible implementation, the first doping source is selected from at least one of the following: TeO3, TiO2, MoO3, WO3, Nb2O5, Ta2O5, V2O5, Sb2O5, SnO2, SiO2, ZrO2, CrO2, Al2O3, La2O3, Y2O3, SrO, MgO, K2CO3, KCl, Co3O4, CoCl2, Fe2O3, FeO, Fe(OH)3, Cu(OH)2, CuO, and CuCl2; and the second doping source is selected from at least one of the following: NaF, LiF, KF, NH4F, Li2S, Na2S, BN, AlN, Si3N4, NH4H2PO4, (NH4)2HPO4, Li3PO4, Na3PO4, H3BO3, and Li3BO3.

[0016] In one possible implementation, the nickel-manganese source is obtained by co-precipitation reaction of a mixed salt solution containing soluble nickel salt and soluble manganese salt at a pH of 7.5-11.5 in the presence of a complexing agent.

[0017] In one possible implementation, the total concentration of nickel and manganese ions in the mixed salt solution is 1-3 mol / L, and the ratio of the concentration of nickel ions to the concentration of manganese ions is 2:3-1:1.

[0018] Thirdly, embodiments of this application also provide a lithium-ion battery, comprising:

[0019] The cathode material as described in the first aspect of claim and any possible embodiment. Attached Figure Description

[0020] Figure 1 XRD comparison images of Embodiment 1, Embodiment 2 and Comparative Example 1 provided for embodiments of this application at diffraction angles 2θ of 25°-55°;

[0021] Figure 2 XRD comparison images of Embodiment 1, Embodiment 2 and Comparative Example 1 provided for embodiments of this application at diffraction angles 2θ of 10°-20°;

[0022] Figure 3 The first charge-discharge curve of the button cell corresponding to Embodiment 1 provided in this application under the conditions of 2.5 to 4.55V and 0.1C.

[0023] Figure 4 The first charge-discharge curve of the button cell corresponding to Embodiment 2 provided in this application under the conditions of 2.5 to 4.55V and 0.1C.

[0024] Figure 5 The first charge-discharge curve of the coin cell corresponding to Comparative Example 1 provided in this application under the conditions of 2.5 to 4.55V and 0.1C.

[0025] Figure 6 A comparison chart of the rate performance of the button cells corresponding to Embodiment 1, Embodiment 2 and Comparative Example 1 provided for the embodiments of this application under conditions of 2.5 to 4.55V;

[0026] Figure 7 The charge-discharge cycle performance of the button cells corresponding to Embodiments 1, 2 and Comparative Example 1 provided in this application under the conditions of 0.33C at a cell voltage of 2.5 to 4.50V. Detailed Implementation

[0027] To address the technical problem of the lack of a manganese-based cathode material with high initial coulombic efficiency and high cycle stability in the existing technology, this application provides a cathode material with high initial coulombic efficiency and high cycle stability, the molecular formula of which is: aNa α Ni λ Mn σ M 1-λ-σ O 2-γ D γ ·(1-a)Li 1+β Ni λ Mn σ M 1-λ-σ O2+β-δ D δ ;0.05≤a≤0.20, 0.60≤α≤0.95, 0<γ≤0.20, 0.04<β<0.10, 0<δ≤0.21, 0.9≤(λ+σ)≤1.0; M is the first dopant element, selected from at least one of Te, Ti, Mo, W, Nb, Ta, V, Sb, Sn, Si, Zr, Cr, Al, Co, Ce, Fe, Cu, La, Y, Sr, Mg, Li, and K; D is the second dopant element, selected from at least one of F, S, P, N, and B.

[0028] In this embodiment, the cathode material includes a sodium-ion material with a P2 phase or a P2-O3 phase composite of O2-0.5, and a composite O3 phase lithium-ion cathode material. On the one hand, since lithium carbonate is priced at 500,000 RMB / ton, the cost of the lithium source accounts for nearly 80% or even higher of the cathode BOM cost, while the cost of sodium carbonate (Na source) is only 2,000-5,000 RMB / ton. Therefore, by reducing the lithium content, the above-mentioned cathode material can reduce the BOM cost by 4-12%. On the other hand, the above-mentioned cathode material has a Ni content with a stoichiometric ratio higher than 0.40, which can alleviate the kinetic polarization phenomenon that occurs in the cathode material during charging and discharging and improve the kinetic performance of the cathode material, thereby effectively improving the average discharge voltage and charge / discharge energy efficiency of the cathode material. Furthermore, the aforementioned cathode material has a low voltage window requirement. Specifically, it can achieve high capacity and energy density when used in lithium-ion half-cells with a voltage window of 4.35–4.5V and when the cathode is Na-type, with a voltage window of approximately 4.05–4.2V. At the same time, this low voltage window is below the critical voltage at which the structure of the P2 phase sodium-ion cathode material deteriorates, thus further improving the cycle stability provided by the embodiments of this application.

[0029] Furthermore, This ensures that the cathode material can provide sufficient capacity through the redox reaction of oxygen anions and transition metal cations at the target voltage window, allowing its specific capacity to be fully utilized. At the same time, since the Ni content is lower than that of ternary cathodes, the cost of the cathode material remains at a low level.

[0030] Furthermore, to ensure the high specific capacity level of the above-mentioned cathode material and the structural stability of the layered structure during charging and discharging within the target voltage window, in one embodiment of this application, 0.08≤a≤0.12, 0.8≤α≤0.95.

[0031] Furthermore, the X-ray diffraction pattern of the aforementioned cathode material includes (002) crystal plane diffraction peaks with diffraction angles of 15.5°-16.1° corresponding to the P2 phase, and (003) crystal plane diffraction peaks with diffraction angles of 18.5°-19.0° corresponding to the O3 phase. Therefore, in the embodiments of this application, the cathode material is a P2-O3 composite phase cathode material.

[0032] Furthermore, in the XRD pattern of this cathode material, the peak intensity ratio of the main peak of the P2 phase (002) crystal plane to the main peak of the O3 phase (003) crystal plane, that is, the peak intensity ratio of the aforementioned (002) crystal plane diffraction peak to the aforementioned (003) crystal plane diffraction peak, is 0.01-0.70.

[0033] Due to the differences in the types of alkali metals and atomic arrangements in the P2 and O3 phases, when the proportion of the P2 phase varies with the value of a in the range of 0.05-0.20, the relative intensity of the main peak (002) of the P2 phase and the main peak (003) of the O3 phase, I(002)P2 / I(003)O3, changes much more than the actual change in the P2 / O3 phase ratio.

[0034] For example, when a = 0.2, i.e., the proportion of P2 phase ≤ 20%, the peak intensity ratio of the main peak of the P2 phase (002) crystal plane to the main peak of the O3 phase (003) crystal plane is between 0.6 and 0.7. For example, when a = 0.05, the peak intensity ratio of the main peak of the P2 phase (002) crystal plane to the main peak of the O3 phase (003) crystal plane is between 0.01 and 0.05.

[0035] Based on the same inventive concept, this application provides a method for preparing the aforementioned cathode material, which simultaneously achieves uniform diffusion of Li and Na within the bulk phase of the cathode material, thereby improving the initial coulombic efficiency and cycle stability of the cathode material. The method includes the following steps:

[0036] The target cathode material was obtained by N-segment sintering of a mixture containing sodium source, lithium source, doped source, and sources of nickel and manganese.

[0037] Wherein, the source of nickel and manganese is a mixture of nickel source and manganese source, and / or, (simultaneously) a source containing nickel and manganese, N is a positive integer, and the sintering temperature of N-segment sintering is not higher than 970℃.

[0038] The molar ratios of the metal elements in the sodium source, lithium source, nickel-manganese precursor, nickel source, and manganese source, as well as the molar ratios of the doping elements in the doping source, are consistent with the stoichiometric ratios of the elements in the target cathode material.

[0039] The aforementioned heating equipment includes, but is not limited to, tube furnaces, muffle furnaces, chamber furnaces, roller kilns, pusher kilns, and rotary kilns.

[0040] The following is a detailed explanation of N-segment sintering.

[0041] When N=1, the sintering temperature is 850-970℃, the holding time is 10-20h, and the heating rate is 2-10℃ / min.

[0042] N=2, and the N-segment sintering includes a first sintering and a second sintering. The sintering temperature of the first sintering is 400-600℃, and the sintering temperature of the second sintering is 850-970℃. The heating rate of the first sintering is 2-10℃ / min, and the holding time is 2-6 hours; the heating rate of the second sintering is 2-10℃ / min, and the holding time is 10-20 hours.

[0043] N=3, and the N-segment sintering includes a first sintering, a second sintering, and a third sintering. The sintering temperature of the first sintering is 400-600℃, the sintering temperature of the second sintering is 650-800℃, and the sintering temperature of the third sintering is 850-970℃. Specifically, the heating rate of the first sintering is 2-10℃ / min, and the holding time is 2-5 hours; the heating rate of the second sintering is 2-10℃ / min, and the holding time is 2-5 hours; the holding time of the third sintering is 10-20 hours.

[0044] The sodium source is selected from at least one of Na2CO3, NaOH, NaNO3, Na2S, and NaCl; the lithium source is selected from LiCO3, LiOH, and LiCl; the nickel source includes NiO; the Mn source includes Mn2O3; the doping source includes a first doping source corresponding to a first doping element, and / or a second doping source corresponding to a second doping element.

[0045] The first doping source is selected from at least one of the following: TeO3, TiO2, MoO3, WO3, Nb2O5, Ta2O5, V2O5, Sb2O5, SnO2, SiO2, ZrO2, CrO2, Al2O3, La2O3, Y2O3, SrO, MgO, K2CO3, KCl, Co3O4, CoCl2, Fe2O3, FeO, Fe(OH)3, Cu(OH)2, CuO, and CuCl2; the second doping source is selected from at least one of the following: NaF, LiF, KF, NH4F, Li2S, Na2S, BN, AlN, Si3N4, NH4H2PO4, (NH4)2HPO4, Li3PO4, Na3PO4, H3BO3, and Li3BO3.

[0046] The aforementioned nickel- and manganese-containing sources are actually molecules with the general formula Ni. θ Mn ρ (OH)2 and / or Ni θMn ρ CO3; a salt precursor. This salt precursor can be obtained by co-precipitation of a mixed salt solution containing soluble nickel and soluble manganese salts at a pH of 7.5-11.5 in the presence of a complexing agent. Specifically, the total concentration of nickel and manganese ions in the mixed salt solution is 1-3 mol / L, and the ratio of the concentration of nickel ions to the concentration of manganese ions is 2:3-1:1.

[0047] The soluble nickel salt is selected from at least one of NiSO4, NiCl2, and Ni(NO3)2. The manganese salt is selected from at least one of MnSO4, MnCl2, and Mn(NO3)2. The complexing agent is selected from at least one of ammonia, ammonium fluoride, and ammonium oxalate.

[0048] To provide an alkaline environment for the entire reaction system, the alkaline solution for the anions is Na₂CO₃ solution and / or NaOH solution. Furthermore, Na... + The total concentration is 1-3 mol / L.

[0049] During the coprecipitation reaction, the internal temperature of the reaction equipment, such as a reactor, is 50-70℃, and the stirring speed is 300-1000rpm, until the preset target particle size or preset weight (corresponding to the number of precursors) is reached, and the above-mentioned salt precursor is obtained.

[0050] Based on the same inventive concept, this application also provides a lithium-ion battery, including the above-mentioned positive electrode material, to improve the initial coulombic efficiency and cycle stability of the lithium-ion battery.

[0051] The following examples and comparative figures illustrate the points.

[0052] Example 1

[0053] S1. Weigh each source according to the stoichiometric ratio of the target product and mix them. Then, use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain the precursor solid powder.

[0054] The source for Na is NaNO3, the source for Li is LiOH, the source for Ni is NiO, and the source for Mn is Mn2O3. The sources for Ti, Al, and Mg are TiO2, Al2O3, and MgO, respectively, and the source for F is NH4F.

[0055] S2. The precursor powder was placed in a pusher kiln and heated to 400℃ at a rate of 2℃ / min, held for 6 hours, then heated to 970℃ at a rate of 2℃ / min and held in air for 10 hours. After cooling in the furnace, the sintered product was ground to obtain 0.05Na. 0.8 (Mn 0.52 Ni 0.48 )0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.9 F 0.1 0.95Li 1.05 (Mn 0.52 Ni 0.48 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.95 F 0.1 .

[0056] Example 2

[0057] S1. Weigh each source according to the stoichiometric ratio of the target product and mix them. Then, use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain the precursor solid powder.

[0058] The Na source is a mixture of NaCl and Na₂CO₃ in a 1:1 molar ratio; the Li source is a mixture of LiCl and Li₂CO₃ in a 1:1 molar ratio; the Ni source is NiO; and the Mn source is Mn₂O₃. The Ti, Al, and Mg sources are TiO₂, Al₂O₃, and MgO, respectively, and the F source is NH₄F.

[0059] S2. The precursor powder was placed in a box furnace and heated to 550℃ at a heating rate of 2℃ / min, held for 4 hours, then heated to 900℃ at a heating rate of 2℃ / min and held in air for 14 hours. After cooling in the furnace, the sintered product was ground to obtain 0.20Na. 0.6 (Mn 0.52 Ni 0.48 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.9 F 0.1 0.80Li 1.05 (Mn 0.52 Ni 0.48 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.95 F 0.1 .

[0060] Example 3

[0061] S1. Weigh each source according to the stoichiometric ratio of the target product and mix them. Then, use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain the precursor solid powder.

[0062] The Na source is a mixture of NaOH and Na₂CO₃ in a 1:1 molar ratio; the Li source is a mixture of LiOH and Li₂CO₃ in a 1:1 molar ratio; the Ni source is NiO; and the Mn source is Mn₂O₃. The Ti, Al, and Mg sources are TiO₂, Al₂O₃, and MgO, respectively, and the F source is NH₄F.

[0063] S2. The precursor powder was placed in a roller kiln and heated to 500℃ at a rate of 5℃ / min, held for 3 hours, then heated to 880℃ at a rate of 5℃ / min and held in air for 16 hours. After cooling in the furnace, the sintered product was ground to obtain 0.10Na. 0.85 (Mn 0.59 Ni 0.41 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.9 F 0.1 0.90Li 1.25 (Mn 0.59 Ni 0.41 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 2.15 F 0.1 .

[0064] Example 4

[0065] S1. Weigh each source according to the stoichiometric ratio of the target product and mix them. Then, use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain the precursor solid powder.

[0066] The Na source is a mixture of NaCl, Na₂CO₃, and NaNO₃ in a molar ratio of 1:1:1; the Li source is a mixture of LiCl, Li₂CO₃, and LiOH in a molar ratio of 1:1:1; the Ni source is NiO; and the Mn source is Mn₂O₃. The Ti, Al, and Mg sources are TiO₂, Al₂O₃, and MgO, respectively, and the F source is NH₄F.

[0067] S2. The precursor powder was placed in a roller kiln and heated to 500℃ at a rate of 2℃ / min, held for 4 hours, then heated to 850℃ at a rate of 2℃ / min and held in air for 18 hours. After cooling in the furnace, the sintered product was ground to obtain the positive electrode material 0.10Na.0.6 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.9 F 0.1 0.90Li 1.15 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 2.05 F 0.1 .

[0068] Example 5

[0069] The preparation method is the same as in Example 4, except that the proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of elements in each source is the same as the stoichiometry of the target cathode material. Specifically, TiO2, Al2O3, and MgO are replaced with appropriate amounts of WO3, Sb2O5, and SnO2 to serve as W source, Sb source, and Sn source, respectively.

[0070] The positive electrode material obtained was 0.10Na. 0.6 (Mn 0.55 Ni 0.45 ) 0.9 (W 0.2 Sn 0.4 Sb 0.4 ) 0.1 O 1.9 F 0.1 0.90Li 1.15 (Mn 0.55 Ni 0.45 ) 0.9 (W 0.2 Sn 0.4 Sb 0.4 ) 0.1 O 2.05 F 0.1 .

[0071] Example 6

[0072] The preparation method is the same as in Example 4, except that the proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of each element in the source is the same as the stoichiometry of the target cathode material. Specifically, TiO2, Al2O3, and MgO are replaced with appropriate amounts of MoO3, ZrO2, and CrO2 to serve as Mo, Zr, and Cr sources, respectively.

[0073] The positive electrode material obtained was 0.10Na. 0.6 (Mn 0.55 Ni 0.45 ) 0.9 (Mo 0.2 Zr 0.4 Cr 0.4 ) 0.1 O 1.9 F 0.1 0.90Li 1.15 (Mn 0.55 Ni 0.45 ) 0.9 (Mo 0.2 Zr 0.4 Cr 0.4 ) 0.1 O 2.05 F 0.1 .

[0074] Example 7

[0075] The preparation method is the same as in Example 4, except that the proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of elements in each source is the same as the stoichiometry of the target cathode material. Specifically, TiO2, Al2O3, and MgO are replaced with appropriate amounts of NH4H2PO4 and H3BO3, respectively, to serve as the P source and B source.

[0076] The positive electrode material obtained was 0.10Na. 0.6 Mn 0.55 Ni 0.45 O 1.8 (F 0.5 P 0.3 B 0.2 ) 0.2 0.90Li 1.15 Mn 0.55 Ni 0.45 O 1.95 (F 0.5 P 0.3 B 0.2 ) 0.2 .

[0077] Example 8

[0078] The preparation method is the same as in Example 4, except that the proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of elements in each source is the same as the stoichiometry of the target cathode material. Specifically, TiO2, Al2O3, MgO, and NH4F are replaced with appropriate amounts of (NH4)2HPO4 and BN to serve as P source, B source, and N source, respectively.

[0079] The positive electrode material obtained was 0.10Na. 0.6 Mn 0.55 Ni 0.45O 1.8 (P 0.4 N 0.3 B 0.3 ) 0.2 0.90Li 1.15 Mn 0.55 Ni 0.45 O 1.95 (P 0.3 N 0.3 B 0.3 ) 0.2 .

[0080] Example 9

[0081] The preparation method is the same as in Example 4. The proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of the elements in each source is the same as the stoichiometry of the target cathode material. In addition, corresponding amounts of Li3PO4 and Li2S are added to the solid powder to serve as P source and S source, respectively, before mixing.

[0082] The positive electrode material obtained was 0.10Na. 0.6 (Mn 0.52 Ni 0.48 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.8 (P 0.3 F 0.4 S 0.3 ) 0.2 0.90Li 1.05 (Mn 0.52 Ni 0.48 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.85 (P 0.3 F 0.4 S 0.3 ) 0.2 .

[0083] Example 10

[0084] The preparation method is the same as in Example 4. The proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of elements in each source is the same as the stoichiometry of the target cathode material. Specifically, NH4F is replaced with corresponding amounts of Li3PO4, AlN, and Li2S to serve as P, N, and S sources, respectively, before mixing.

[0085] The positive electrode material obtained was 0.10Na. 0.6 (Mn0.59 Ni 0.41 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.8 (P 0.3 N 0.4 S 0.3 ) 0.2 0.90Li 1.25 (Mn 0.59 Ni 0.41 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 2.05 (P 0.3 N 0.4 S 0.3 ) 0.2 .

[0086] Example 11

[0087] The preparation method is the same as in Example 4. The proportions of each source are adjusted according to the stoichiometry of the target cathode material so that the molar ratio of elements in each source is the same as the stoichiometry of the target cathode material. Specifically, NH4F is replaced with corresponding amounts of Li3PO4, AlN, and Li2S to serve as P, N, and S sources, respectively, before mixing.

[0088] The positive electrode material obtained was 0.10Na. 0.8 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.8 (P 0.3 N 0.4 S 0.3 ) 0.2 0.90Li 1.15 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.95 (P 0.3 N 0.4 S 0.3 ) 0.2 .

[0089] Example 12

[0090] S1. Weigh the raw materials according to the stoichiometric ratio of the elements in the precursor, and prepare salt solution, alkaline solution, and complexing agent solution. Simultaneously pump all three into a reactor for co-precipitation. Maintain the pH of the reactor at 10.5–11.0, the stirring speed at 600 rpm, and the reaction temperature at 55℃. When the precursor precipitate reaches 6.5–7.0 μm, finely adjust the pH to maintain the particle size. Continue the reaction until the theoretical dry material weight reaches 10 kg, then stop feeding. After aging, washing, and drying, the secondary spherical precursor Mn is obtained. 0.55 Ni 0.45 (OH)2.

[0091] In the salt solution, the Ni and Mn salts are NiSO4 and MnSO4, respectively, and the total concentration of metal ions in the mixed salt solution is 2 mol / L; the alkaline solution is NaOH solution, and the Na in the alkaline solution is... + The total concentration is 2 mol / L; the complexing agent is an ammonia solution with a total solute molecule concentration of 0.2 mol / L.

[0092] S2. Weigh each source and precursor according to the stoichiometric ratio of the target product, mix them, and use ball milling to mix the mixture evenly in a high-energy ball mill to obtain precursor solid powder.

[0093] The Na source is Na2CO3, the Li source is LiCO3, and the Ti, Al, Mg, S, N, and P sources are TiO2, Al2O3, MgO, Li2S, AlN, and NH4H2PO4, respectively.

[0094] S3. The precursor powder was placed in a box furnace and heated to 500℃ at a heating rate of 2℃ / min, and held at that temperature for 4 hours. Then, the temperature was increased to 850℃ at a heating rate of 2℃ / min and held at that temperature in air for 15 hours. After cooling in the furnace, the sintered product was ground to obtain 0.10Na. 0.6 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.8 (P 0.3 N 0.4 S 0.3 ) 0.2 0.90Li 1.05 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.85 (P0.3 N 0.4 S 0.3 ) 0.2 .

[0095] Example 13

[0096] Except for replacing the alkaline solution with Na₂CO₃ solution and maintaining the pH of the reactor at 7.6–8.4, the other preparation parameters and implementation steps were the same as in Example 12, yielding 0.10Na 0.6 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.8 (P 0.3 N 0.4 S 0.3 ) 0.2 0.90Li 1.05 (Mn 0.55 Ni 0.45 ) 0.9 (Ti 0.4 Al 0.4 Mg 0.2 ) 0.1 O 1.85 (P 0.3 N 0.4 S 0.3 ) 0.2 .

[0097] Example 14

[0098] Except for the stoichiometry of the target cathode material and the adjustment of the corresponding source ratios, the Ni and Mn sources in the salt solution were replaced with NiNO3 and MnNO3, respectively, and TiO2, Al2O3, Li2S, and AlN were replaced with appropriate amounts of V2O5, SrO, LiF, and Li3BO3, respectively, to serve as V, Sr, F, and B sources. Other preparation parameters and implementation steps were consistent with Example 12, yielding 0.05Na 0.7 (Mn 0.59 Ni 0.41 ) 0.9 (V 0.4 Sr 0.4 Mg 0.2 ) 0.1 O 1.8 (P 0.3 F 0.4 B 0.3 ) 0.2 0.95Li 1.25 (Mn 0.59 Ni 0.41) 0.9 (V 0.4 Sr 0.4 Mg 0.2 ) 0.1 O 2.05 (P 0.3 F 0.4 B 0.3 ) 0.2 .

[0099] Example 15

[0100] Except for the stoichiometry of the target cathode material and the adjustment of the corresponding source ratios, the Na source was replaced with NaOH, the Li source with LiOH, and TiO2, Al2O3, Mg, Li2S, and AlN were replaced with appropriate amounts of Ta2O5, Y2O3, KCl, LiF, and Li3BO3 as Ta, Y, K, F, and B sources, respectively. Other preparation parameters and implementation steps were consistent with Example 12, yielding 0.15Na 0.7 (Mn 0.59 Ni 0.41 ) 0.9 (Ta 0.2 Y 0.4 K 0.4 ) 0.1 O 1.8 (P 0.3 F 0.4 B 0.3 ) 0.2 0.85Li 1.25 (Mn 0.59 Ni 0.41 ) 0.9 (Ta 0.2 Y 0.4 K 0.4 ) 0.1 O 2.05 (P 0.3 F 0.4 B 0.3 ) 0.2 .

[0101] Example 16

[0102] Except for the stoichiometry of the target cathode material and the adjustment of the corresponding source ratios, the Na source was replaced with NaOH, the Li source with LiOH, and TiO2, Al2O3, MgO, Li2S, and AlN were replaced with appropriate amounts of Ta2O5, Y2O3, KCl, LiF, and Li3BO3 to serve as Ta, Y, K, F, and B sources, respectively. Other preparation parameters and implementation steps were consistent with Example 12, yielding 0.15Na 0.7 (Mn 0.59 Ni 0.41 )0.9 (Ta 0.2 Y 0.4 K 0.4 ) 0.1 O 1.8 (P 0.3 F 0.4 B 0.3 ) 0.2 0.85Li 1.25 (Mn 0.59 Ni 0.41 ) 0.9 (Ta 0.2 Y 0.4 K 0.4 ) 0.1 O 2.05 (P 0.3 F 0.4 B 0.3 ) 0.2 .

[0103] Comparative Example 1

[0104] S1. Weigh each source according to the stoichiometric ratio of the target product and mix them. Then, use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain the precursor solid powder.

[0105] Among them, the Li source is LiCO3, the Ni source is NiO, and the Mn source is Mn2O3.

[0106] S2. The precursor powder was placed in a muffle furnace and heated to 400℃ at a heating rate of 2℃ / min, held for 6 hours, then heated to 970℃ at a heating rate of 2℃ / min and held for 10 hours in air. After cooling in the furnace, the sintered product was ground to obtain Li. 1.05 (Ni 0.48 Mn 0.52 )O 1.95 F 0.1 .

[0107] Comparative Example 2

[0108] S1. Weigh each source according to the stoichiometric ratio of the target product and mix them. Then, use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain the precursor solid powder.

[0109] The Li source is LiCO3, the Ni source is NiO, and the Mn source is Mn2O3.

[0110] S2. The precursor powder was placed in a muffle furnace and heated to 500℃ at a heating rate of 5℃ / min, held for 3 hours, then heated to 880℃ at a heating rate of 5℃ / min and held in air for 16 hours. After cooling in the furnace, the sintered product was ground to obtain Li. 1.25 (Ni0.41 Mn 0.59 )O 2.15 F 0.1 .

[0111] Comparative Example 3

[0112] S1. Weigh the raw materials according to the stoichiometric ratio of the elements in the precursor, and prepare salt solution, alkaline solution, and complexing agent solution. Simultaneously pump all three into a reactor for co-precipitation. Maintain the pH of the reactor at 10.5–11.0, the stirring speed at 600 rpm, and the reaction temperature at 55℃. When the precursor precipitate reaches 6.5–7.0 μm, finely adjust the pH to maintain the particle size. Continue the reaction until the theoretical dry material weight reaches 10 kg, then stop feeding. After aging, washing, and drying, the secondary spherical precursor Mn is obtained. 0.41 Ni 0.59 (OH)2.

[0113] In the salt solution, the Ni and Mn salts are NiSO4 and MnSO4, respectively, and the total concentration of metal ions in the mixed salt solution is 2 mol / L; the alkaline solution is NaOH solution, and the Na in the alkaline solution is... + The total concentration is 2 mol / L; the complexing agent is an ammonia solution with a total solute molecule concentration of 0.2 mol / L.

[0114] S2. Weigh the lithium source and precursor according to the stoichiometric ratio of the target product, mix them, and then use a ball mill to mix the mixture evenly in a high-energy ball mill to obtain a precursor solid powder. The Li source is LiCO3.

[0115] S3. The precursor powder was placed in a box furnace and heated to 500℃ at a heating rate of 2℃ / min, and held at that temperature for 3 hours. Then, the temperature was increased to 880℃ at a heating rate of 2℃ / min and held at that temperature in air for 16 hours. After cooling in the furnace, the sintered product was ground to obtain Li. 1.25 (Ni 0.41 Mn 0.59 )O 2.15 F 0.1 .

[0116] Comparative Example 4

[0117] Except for replacing the alkaline solution with Na₂CO₃ solution and maintaining the pH of the reactor at 7.6–8.4, the other preparation parameters and procedures were the same as in Comparative Example 3, yielding Li. 1.25 (Ni 0.41 Mn 0.59 )O 2.15 F 0.1 .

[0118] Comparative Example 5

[0119] The implementation steps are the same as in Example 16:

[0120] S1. Weigh the raw materials according to the stoichiometric ratio of the elements in the precursor, and prepare salt solution, alkaline solution, and complexing agent solution. Simultaneously pump all three into a reactor for co-precipitation. Maintain the pH of the reactor at 10.5–11.0, the stirring speed at 600 rpm, and the reaction temperature at 55℃. When the precursor precipitate reaches 6.5–7.0 μm, finely adjust the pH to maintain the particle size. Continue the reaction until the theoretical dry material weight reaches 10 kg, then stop feeding. After aging, washing, and drying, the secondary spherical precursor Mn is obtained. 0.59 Ni 0.41 (OH)2.

[0121] In the salt solution, the Ni and Mn salts are NiSO4 and MnSO4, respectively, and the total concentration of metal ions in the mixed salt solution is 2 mol / L; the alkaline solution is NaOH solution, and the Na in the alkaline solution is... + The total concentration is 2 mol / L; the complexing agent is an ammonia solution with a total solute molecule concentration of 0.2 mol / L.

[0122] S2. Weigh each source and precursor according to the stoichiometric ratio of the target product, mix them, and use ball milling to mix the mixture evenly in a high-energy ball mill to obtain precursor solid powder.

[0123] The Li source is LiOH, and the Ta, Y, K, F, B, and P sources are Ta2O5, Y2O3, KCl, LiF, Li3BO3, and NH4H2PO4, respectively.

[0124] S3. The precursor powder was placed in a box furnace and heated to 500℃ at a heating rate of 2℃ / min, and held at that temperature for 4 hours. Then, the temperature was increased to 850℃ at a heating rate of 2℃ / min and held at that temperature in air for 15 hours. After cooling in the furnace, the sintered product was ground to obtain Li. 1.25 (Mn 0.59 Ni 0.41 ) 0.9 (Ta 0.2 Y 0.4 K 0.4 ) 0.1 O- 2.05 (P 0.3 F 0.4 B 0.3 ) 0.2 .

[0125] Furthermore, XRD tests were performed on Examples 1, 2, and Comparative Example 1 to obtain their respective XRD patterns. Figure 1 The images show XRD comparisons of Example 1, Example 2, and Comparative Example 1 at diffraction angles 2θ ranging from 25° to 55°. Figure 2The images show a comparison of XRD patterns for Examples 1, 2, and Comparative Example 1 at diffraction angles 2θ of 10°–20°. Figures 1-2 It can be seen that when Na in the composite phase material α Ni λ Mn σ M 1-λ-σ O 2- When the proportion of γDγ is as low as a = 0.05, the XRD shows the characteristic main peak (002) of the P2 phase, and its spectral characteristics differ from those of the pure O3 lithium-rich cathode in Comparative Example 1. When the proportion of NaαNiλMnσM1-λ-σO2-γDγ in Example 2 is a = 0.20, the XRD spectrum shows a significant difference from that in Comparative Example 1. Significant characteristic peaks of the P2 phase appear in many places in the XRD spectrum of Example 2.

[0126] Furthermore, secondary batteries were prepared using the cathode materials in the examples and comparative examples. The specific steps were as follows: composite cathode powder was mixed with conductive agent Super-P and binder PVDF at a mass ratio of 92:4:4. An appropriate amount of NMP solution was added to form a slurry, which was then coated onto aluminum foil and dried in a vacuum oven at 150°C for 12 hours. Subsequently, secondary batteries were assembled in an Ar atmosphere glove box, using lithium metal as the negative electrode and 1 mol / L LiPF6 dissolved in a mixed organic solvent with a volume ratio of EC:EMC = 3:7 as the electrolyte, to form coin-type CR2032 batteries.

[0127] Furthermore, a constant current and constant voltage charging and constant current discharging charging-discharging mode is used, with 1C = 250mAg. -1 The current density was tested at 0.1C rate, and the first charge-discharge cycle was performed in the voltage window of 2.5 to 4.55V for activation and rate testing. Subsequently, 100 cycles were performed at 0.33C in the range of 2.5 to 4.5V. The test results are shown in Table 1 below.

[0128] Table 1

[0129]

[0130] As shown in Table 1, the initial coulombic efficiency and cycle stability of Examples 1-16 are better than those of Comparative Examples 1-5.

[0131] Figure 3 The first charge-discharge curve of the coin cell corresponding to Example 1 under conditions of 2.5–4.55V and 0.1C is shown. Figure 4 The first charge-discharge curve of the button cell corresponding to Example 2 under conditions of 2.5–4.55V and 0.1C is shown. Figure 5 The first charge-discharge curve of the coin cell corresponding to Comparative Example 1 under conditions of 2.5–4.55V and 0.1C is shown for comparison. Figure 3-5It can be seen that in Example 1 with a = 0.05, the composite cathode capacity utilization and initial efficiency are significantly better than those in Comparative Example 1, achieving lower cost and higher capacity utilization. When a = 0.20, the composite cathode capacity in Example 2 significantly decreases to be close to that in Comparative Example 1 compared with Example 1, but the initial efficiency is further improved, achieving lower cost and the same capacity utilization.

[0132] Figure 6 Figure for comparing the rate performance of the coin cells corresponding to Example 1, Example 2 and Comparative Example 1 under the condition of 2.5 - 4.55V; Figure 6 It can be obtained that there is no significant difference in the rate performance of the cathode materials in Example 1 and Example 2 compared with the O3 pure - phase lithium - rich cathode described in Comparative Example 1, indicating that the composite cathode can also achieve good rate performance.

[0133] Figure 7 Figure for the charge - discharge cycle performance of the coin cells corresponding to Example 1, Example 2 and Comparative Example 1 under the condition of 0.33C at 2.5 - 4.50V. Figure 7 It can be obtained that the cycle performance of the cathode materials in Example 1 and Example 2 is slightly better than that of the O3 pure - phase lithium - rich cathode described in Comparative Example 1.

[0134] Obviously, those skilled in the art can make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalent technologies, this application also intends to include these changes and modifications.

Claims

1. A positive electrode material, characterized in that, The general molecular formula of the cathode material is: aNa α Ni λ Mn σ M 1-λ-σ O 2-γ D γ (1-a)Li 1+β Ni λ Mn σ M 1-λ-σ O 2+β-δ D δ ;0.08≤a≤0.20, 0.60≤α≤0.95, 0<γ≤0.20, 0.04<β<0.10, 0<δ≤0.21, And 0.9≤(λ+σ)≤1.0; M is the first doping element, and M is selected from at least one of Te, Ti, Mo, W, Nb, Ta, V, Sb, Sn, Si, Zr, Cr, Al, Co, Ce, Fe, Cu, La, Y, Sr, Mg, Li, and K; D is the second doping element, and D is selected from at least one of F, S, P, N, and B.

2. The cathode material as described in claim 1, characterized in that, The cathode material is a P2-O3 composite phase material; the X-ray diffraction pattern of the cathode material includes: (002) crystal plane diffraction peaks with diffraction angles of 15.5°-16.1° corresponding to the P2 phase, and (003) crystal plane diffraction peaks with diffraction angles of 18.5°-19.0° corresponding to the O3 phase, and the ratio of the peak intensity of the (002) crystal plane diffraction peaks to the peak intensity of the (003) crystal plane diffraction peaks is 0.01-0.

70.

3. The positive electrode material as described in claim 1, characterized in that, 0.08≤a≤0.12, 0.8≤α≤ 0.95。 4. A method for preparing the cathode material according to any one of claims 1-3, characterized in that, include: The target cathode material is obtained by N-segment sintering a mixture of sodium source, lithium source, doped source, and nickel and manganese source; wherein the nickel and manganese source is a mixture of nickel source and manganese source, and / or a source containing nickel and manganese, N is a positive integer, and the sintering temperature of the N-segment sintering is not higher than 970℃. The ratio of nickel ion concentration to manganese ion concentration in the nickel and manganese source is 2:3 to 1:

1.

5. The method as described in claim 4, characterized in that, The N-segment sintering includes a first sintering and a second sintering, wherein the sintering temperature of the first sintering is 400-600℃ and the sintering temperature of the second sintering is 850-970℃.

6. The method as described in claim 4 or 5, characterized in that, The sodium source is selected from at least one of Na₂CO₃, NaOH, NaNO₃, Na₂S, and NaCl; the lithium source is selected from LiCO₃, LiOH, and LiCl; the nickel source includes NiO; the Mn source includes Mn₂O₃; the doping source includes a first doping source corresponding to a first doping element, and / or a second doping source corresponding to a second doping element; the nickel- and manganese-containing source is selected from Ni θ Mn ρ (OH)2 and / or Ni θ Mn ρ CO3; among which, .

7. The method as described in claim 6, characterized in that, The first doping source is selected from at least one of the following: TeO3, TiO2, MoO3, WO3, Nb2O5, Ta2O5, V2O5, Sb2O5, SnO2, SiO2, ZrO2, CrO2, Al2O3, La2O3, Y2O3, SrO, MgO, K2CO3, KCl, Co3O4, CoCl2, Fe2O3, FeO, Fe(OH)3, Cu(OH)2, CuO, and CuCl2; the second doping source is selected from at least one of the following: NaF, LiF, KF, NH4F, Li2S, Na2S, BN, AlN, Si3N4, NH4H2PO4, (NH4)2HPO4, Li3PO4, Na3PO4, H3BO3, and Li3BO3.

8. The method as described in claim 4, characterized in that, The nickel and manganese source is obtained by co-precipitation reaction of a mixed salt solution containing soluble nickel salt and soluble manganese salt at a pH of 7.5-11.5 in the presence of a complexing agent; the total concentration of nickel ions and manganese ions in the mixed salt solution is 1-3 mol / L.

9. A lithium-ion battery, characterized in that, include: The cathode material according to any one of claims 1-3.

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