Lithium-rich cathode material, preparation method thereof and lithium ion battery

Abstract

This invention provides a lithium-rich cathode material, its preparation method, and a lithium-ion battery. By controlling the crystal phase structure of the lithium-rich cathode material to be O2 phase and the intensity ratio of characteristic peaks in the XRD diffraction pattern, the cycle stability of the lithium-rich cathode material can be effectively improved. The general molecular formula of this lithium-rich cathode material is: Li x Ni a Mn b M c O 2‑d M' d , 0.87≤x≤1.05, 0.75<a+b+c<0.78, 0.42≤a / b≤0.67, 0≤c≤0.02, 0≤d≤0.02, M is at least one of Ta, Nb, W, Ti, Fe, Sb, Sn, Ce, Al, Si, Co, Zn, Mg, and K, and M' is one or more of P, S, and F; wherein, in the XRD pattern of the lithium-rich cathode material, the main peak is the O2 phase, the ratio of the intensity of the first main peak to the intensity of the second main peak is 1.3-1.8; the diffraction angle of the main peak is 18.3°-18.5°, the diffraction angle of the first main peak is 44.3°-44.7°, and the diffraction angle of the second main peak is 36.6°-37°.

Description

Technical Field

[0001] This invention relates to the field of cathode materials technology for energy storage batteries, and particularly to a lithium-rich cathode material and its preparation method, as well as lithium-ion batteries. Background Technology

[0002] Among lithium-rich cathode materials for lithium-ion batteries, lithium-rich manganese-based materials xLiMnO2·(1-x)Li2MnO3 have attracted much attention due to their excellent cycle stability and high capacity. Existing lithium-rich manganese-based materials have an O3-type structure. When cycling at higher voltage windows (>4.5V vs graphene), this structure exhibits transition metal ion migration and a transformation of the layered structure to the spinel phase, leading to a decrease in coulombic efficiency and a gradual decay of the discharge specific capacity. Simultaneously, increased polarization and a larger average charge-discharge voltage difference result in significant voltage hysteresis. This further contributes to a continuous decrease in the average discharge voltage, leading to voltage decay. Therefore, there is a lack of lithium-rich cathode materials with good cycle stability in the current technology. Summary of the Invention

[0003] This invention provides a lithium-rich cathode material and its preparation method, as well as a lithium-ion battery. By controlling the crystal phase structure type of the lithium-rich cathode material to be O2 phase and the intensity ratio of characteristic peaks in the XRD diffraction pattern, the cycle stability of the lithium-rich cathode material can be effectively improved.

[0004] In a first aspect, embodiments of this application provide a lithium-rich cathode material, the general molecular formula of which is: Li x Ni a Mn b M c O 2-d M' d , 0.87≤x≤1.05, 0.75<a+b+c<0.78, 0.42≤a / b≤0.67, 0≤c≤0.02, 0≤d≤0.02, M is at least one of Ta, Nb, W, Ti, Fe, Sb, Sn, Ce, Al, Si, Co, Zn, Mg, and K, and M' is one or more of P, S, and F; wherein,

[0005] In the XRD pattern of the lithium-rich cathode material, the main peak is the O2 phase, and the intensity ratio of the first main peak to the second main peak is 1.3-1.8; the diffraction angle of the main peak is 18.3°-18.5°, the diffraction angle of the first main peak is 44.3°-44.7°, and the diffraction angle of the second main peak is 36.6°-37°.

[0006] The lithium-rich cathode material with O2 phase as the main phase provided in this application has the advantage of suitable lattice defect and vacancy content. On the one hand, it avoids the problem in existing lithium-rich cathode materials where the ratio of the first main peak to the second main peak is too high, resulting in low lattice defect and vacancy content, leading to rapid stress concentration and destruction of the structural stability of the lithium-rich cathode material during charge-discharge. On the other hand, it avoids the problem in existing lithium-rich cathode materials where the ratio of the first main peak to the second main peak is low, resulting in high lattice defect and vacancy content, causing instability of the surface and crystal framework of the lithium-rich cathode material. Based on the above two aspects, the lithium-rich cathode material provided in this application has high cycle stability. Furthermore, because the energy barrier for the migration of transition metals from the transition metal layer in the O2 phase to the alkali metal layer is higher than that of cathode materials with other crystal phase structures, such as the O3 phase, the phenomenon of irreversible migration of interlayer cations during charge-discharge can be effectively alleviated, thereby further improving the cycle stability of the lithium-rich cathode material.

[0007] In one possible implementation, the intensity ratio of the second primary peak to the intensity of the primary peak is 0.15-0.30; the full width at half maximum (FWHM) of the first primary peak... A ≥0.5°, the full width at half maximum (FWHM) of the second main peak B ≥0.4°.

[0008] In one possible implementation, the specific surface area of ​​the lithium-rich cathode material is 1.0-4.0 m². 2 / g; the median particle size of the lithium-rich cathode material is 3.0-12.0μm.

[0009] In one possible implementation, the lithium-rich cathode material has a compaction density of not less than 2.7 g / cm³ under a pressure of 3.0 T. 3 The tap density of the lithium-rich cathode material is 2.0-3.0 g / cm³. 3 .

[0010] One possible implementation is that the surface of the lithium-rich cathode material contains CO3. 2- The content is 0.01wt%-0.5wt%, OH - The content is 0.01wt%-0.25wt%, Na + Content less than 0.005 wt%.

[0011] Secondly, embodiments of this application provide a method for preparing a lithium-rich cathode material as described in the first aspect and any possible implementation, comprising:

[0012] Under conditions of pH not lower than 7.5 and temperature of 50-70℃, a co-precipitation reaction is carried out between a salt solution, an alkaline solution, and a complexing agent to generate a precursor with a particle size distribution (SPAN) of 1.2-1.8. The molar ratio of nickel ions to manganese ions in the salt solution corresponds to the stoichiometric ratio of nickel to manganese in the lithium-rich cathode material. The particle size distribution...

[0013] A first mixture including the precursor and sodium salt is subjected to a multi-stage sintering process to obtain a sodium-containing precursor; wherein the sintering temperature in the multi-stage sintering process increases sequentially, the temperature of the first stage sintering process in the multi-stage sintering process is 400-600℃, and the sintering time of the first stage sintering process is 3-8 hours.

[0014] The second mixture, comprising the sodium-containing precursor and the lithium source, is sintered at 350-500°C for 5-20 hours to obtain the lithium-rich cathode material.

[0015] In one embodiment of this application, the concentration of metal ions in the salt solution is 1-2 mol / L, and the concentration of sodium ions in the alkaline solution is 1-2 mol / L; when the complexing agent enters the reaction device in the form of a complexing agent solution, the concentration of the complexing agent in the complexing agent solution is 0.02-0.2 mol / L.

[0016] In one possible implementation, the solute in the salt solution includes NiSO4 and MnSO4; the solute in the alkaline solution includes at least one of NaOH, Na2CO3, and NaHCO3.

[0017] In one possible implementation, the complexing agent is selected from at least one of: ammonia, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ascorbic acid, and sodium dodecyl sulfate.

[0018] One possible implementation involves co-precipitating a salt solution, an alkaline solution, and a complexing agent solution under conditions of pH not lower than 7.5 and temperature of 50-70°C to generate a target precursor with a particle size distribution (SPAN) of 1.2-1.8, comprising:

[0019] The salt solution, the alkaline solution, and the complexing agent solution containing the complexing agent are subjected to a co-precipitation reaction under conditions of pH 7.5-11.0 to generate an intermediate precursor with an intermediate median particle size, thereby obtaining an intermediate slurry.

[0020] The pH value of the intermediate slurry is increased so that the median particle size variation of the intermediate precursor in the intermediate slurry does not exceed 0.6 μm, thereby obtaining a target precursor with a particle size distribution SPAN of 1.2-1.8; wherein the difference between the pH value of the intermediate slurry after the increase and the pH value before the increase does not exceed 1.

[0021] In one possible implementation, the molar ratio of sodium to the sum of nickel and manganese in the precursor in the first mixture satisfies the following relationship:

[0022] In one possible implementation, the first mixture further includes at least one of the following: Ta source, Ti source, W source, Fe source, Sb source, Sn source, Ce source, Zn source, Mg source, K source, P source, S source, and F source.

[0023] In one embodiment of this application, the multi-stage sintering process is a two-stage sintering process, wherein the temperature of the second stage sintering process is 800-950℃ and the sintering time is 10-20h.

[0024] In one possible implementation, the second mixture further includes at least one source selected from Ta, Ti, W, Fe, Sb, Sn, Ce, Zn, Mg, K, P, S, and F; in the second mixture, the molar ratio between lithium and the sum of nickel and manganese in the sodium-containing precursor is [missing information].

[0025] One possible implementation, after obtaining the target lithium-rich cathode material, further includes:

[0026] The target lithium-rich cathode material was washed with water and centrifuged to obtain a water-containing lithium-rich cathode material.

[0027] The aqueous lithium-rich cathode material is dried at 120-160℃.

[0028] Thirdly, embodiments of this application also provide a lithium-ion battery, comprising:

[0029] The lithium-rich cathode material as described in the first aspect and any possible embodiment, or the lithium-rich cathode material prepared by the method described in the second aspect and any possible embodiment. Attached Figure Description

[0030] Figure 1 A flowchart illustrating the preparation of lithium-rich cathode materials is provided in this application embodiment;

[0031] Figure 2 The X-ray diffraction pattern of Example 1 provided in this application;

[0032] Figure 3 Electron scanning microscope image of Embodiment 1 provided in this application;

[0033] Figure 4The X-ray diffraction pattern of Example 8 provided in this application;

[0034] Figure 5 The X-ray diffraction pattern of Comparative Example 1 provided in the embodiments of this application;

[0035] Figure 6 Electron scanning microscope image for comparative example 1 provided in this application;

[0036] Figure 7 Comparison of main peaks in the X-ray diffraction patterns of Examples 1, 8 and Comparative Example 1 provided for the embodiments of this application;

[0037] Figure 8 The discharge curve of Example 1 provided for the embodiments of this application was tested under 1.0C conditions for 100 cycles;

[0038] Figure 9 The discharge curve of Example 8 provided for this application embodiment was tested under 1.0C conditions for 100 cycles;

[0039] Figure 10 The discharge curve of Comparative Example 1 provided for the embodiments of this application was tested under 1.0C conditions for 100 cycles. Detailed Implementation

[0040] For ease of understanding, the technical terms mentioned in the embodiments of this application are explained below:

[0041] Tapped density: The mass per unit volume of powder in a container after it has been tapped under specified conditions. Tapping indicates that the powder has been vibrated to break down its voids and achieve its ultimate bulk density.

[0042] Compacted density: refers to the density of the positive / negative electrode material after it has been compacted onto the electrode sheet. Higher compacted density results in higher battery capacity and energy density. The expression for compacted density is: Compacted density = Areal density / (Thickness of the electrode sheet after compaction - Thickness of the current collector).

[0043] Specific surface area: The total area of ​​a unit mass of material.

[0044] First-cycle coulombic efficiency: defined as the ratio of discharge capacity to charge capacity in the first charge-discharge cycle of a lithium-ion battery. First-cycle coulombic efficiency is one of the performance indicators for quantifying the anode materials of lithium-ion batteries.

[0045] Battery capacity: The amount of electricity a battery can discharge under certain conditions (discharge rate, temperature, termination voltage, etc.) (discharge test can be performed using JS-150D). Unit: Ampere-hour (abbreviated as A·H, 1A·h = 3600C).

[0046] Energy density: The energy released per unit mass or unit volume of a battery, also known as volumetric energy density or gravimetric energy density. For cathode materials or lithium-ion batteries, both energy density and power density are variables. After multiple uses, the energy density (battery capacity) and power density of a lithium-ion battery will decrease.

[0047] To address the problem of poor cycle stability in existing lithium-rich cathode materials due to intracrystalline phase transitions and ion migration during charge-discharge cycles, this application provides a lithium-rich cathode material with the general molecular formula Li. x Ni a Mn b M c O 2-d M' d , 0.87≤x≤1.05, 0.75<a+b+c<0.78, 0.42≤a / b≤0.67, 0≤c≤0.02, 0≤d≤0.02, M is at least one of Ta, Nb, W, Ti, Fe, Sb, Sn, Ce, Al, Si, Co, Zn, Mg, and K, and M' is one or more of P, S, and F.

[0048] In the XRD pattern of the aforementioned lithium-rich cathode material, the main peak is the O2 phase, and the intensity ratio of the first main peak to the second main peak is 1.3-1.8; the diffraction angle of the main peak is 18.3°-18.5°, the diffraction angle of the first main peak is 44.3°-44.7°, and the diffraction angle of the second main peak is 36.6°-37°.

[0049] In the lithium-rich cathode material provided in this application embodiment, lithium is only 10%-40% in excess of the transition metal elements. While exhibiting a high specific capacity, this lithium-rich cathode material improves the utilization rate of lithium. Furthermore, the Ni content is slightly higher than that in existing lithium-rich cathode materials. Without affecting the specific capacity, this improves the kinetic performance of the lithium-rich cathode material, increases the average discharge voltage, and thus effectively enhances its energy density, rate performance, and cycle stability.

[0050] Furthermore, the main peak in this XRD pattern is the highest diffraction peak among all diffraction peaks. When the aforementioned main peak is the O2 phase, since XRD testing has consistent sensitivity in detecting crystallinity, atomic number in the crystal phase composition, and similar primary particle size of crystal phases, the main peak corresponds to the most abundant crystal phase type in the lithium-rich cathode material. Therefore, the lithium-rich cathode material in this embodiment is a lithium-rich cathode material with O2 phase as the main phase (content not less than 80%).

[0051] Since different phases in the same cathode material have the same atomic composition, and the main phase in the crystal structure can play a decisive role in the performance of the cathode material, the performance of the lithium-rich cathode material provided in the embodiments of this application is actually determined by the O2 phase in its crystal structure.

[0052] Furthermore, in the XRD pattern, the intensity I of the first main peak... A Intensity I of the second main peak B The ratio of I A / I B The ratio is between 1.3 and 1.8, ensuring that the lattice defects and vacancy content in the lithium-rich cathode material provided in this application embodiment are appropriate, so that the lithium-rich cathode material exhibits excellent structural stability when the upper limit of the voltage window is 4.45-4.6V. On the one hand, it can effectively alleviate the lattice stress caused by lithium-ion deintercalation and reintercalation during the charge-discharge process, that is, it avoids the problem of poor cycle stability caused by the low lattice defect and vacancy content due to the ratio of the intensity of the first main peak and the second main peak of the same diffraction angle being greater than 2 in the O3 phase lithium-rich cathode material of the prior art, which is difficult to resist the lattice stress. On the other hand, it can also avoid the problem of poor crystallinity, unstable crystal framework and interface caused by the ratio of the first main peak and the second main peak of the same diffraction angle within the same range being less than 1.2 in the O2 phase lithium-rich cathode material of the prior art, which leads to poor crystallinity, unstable crystal framework and interface, and thus poor cycle stability caused by the easy collapse of the layered structure with lithium-ion deintercalation during the charge-discharge process.

[0053] It should be noted that, in the embodiments of this application, the diffraction angle of any peak is the highest point of the diffraction peak, that is, the diffraction angle 2*theta corresponding to the peak top.

[0054] The following further explains the O2 phase. In lithium-rich cathode materials with O2 as the main phase, the O anion stacking sequence is ABAC. Compared to the O3 main phase crystal structure with the stacking sequence ABCABC, in the O2 main phase lithium-rich cathode material crystal structure, Ni / Mn / Li cations in the transition metal layer arbitrarily occupy MO6 octahedral sites; in the alkali metal layer, Li ions occupy LiO2 octahedral sites. This crystal structure results in a higher energy barrier for the migration of transition metals from the transition metal layer to the alkali metal layer in the O2 structure after deep delithiation caused by the first charge cycle. This suppresses the problem of irreversible cation migration in the transition metal layer reducing the stability of the crystal structure during charge-discharge. Correspondingly, the phase transition phenomenon caused by irreversible cation migration between layers is weakened during charge-discharge in the O2 main phase lithium-rich cathode material, effectively improving the problem of continuous decay of the average discharge voltage caused by phase transition, and exhibiting excellent voltage stability and cycle performance.

[0055] Furthermore, the reversibility of anion redox in the O2-phase-dominant crystal structure is higher than that in existing O3-phase-dominant lithium-rich cathode materials, thus exhibiting high capacity, high energy density, and high first-time coulombic efficiency.

[0056] It should be noted that in the embodiments of this application, the distinction between the O3 phase and the O2 phase is made, and the determination that the crystal phase structure of the above-mentioned lithium-rich cathode material is dominated by the O2 phase is based on the diffraction angle of the main peak in the XRD pattern. Specifically, the main peak (002) in the XRD pattern of the O2 phase is slightly shifted to the left compared to the main peak (003) in the XRD pattern of the O3 phase. The diffraction angle of the main peak (002) in the XRD pattern of the O2 phase is 2*theta = 18.3-18.5°, while the diffraction angle of the main peak (003) in the XRD pattern of the O3 phase is 2*theta = 18.5-18.8°.

[0057] Furthermore, the intensity ratio of the second main peak to the main peak is 0.15-0.30, and the full width at half maximum (FWHM) of the first main peak is... A ≥0.5°, the full width at half maximum (FWHM) of the second main peak B ≥0.4°.

[0058] The aforementioned half-width at half-maximum (HWHM) is the peak width corresponding to half the height of the diffraction peak.

[0059] Furthermore, to avoid the problem of decreased stability caused by an excessively large specific surface area, in one embodiment of this application, the specific surface area of ​​the above-mentioned lithium-rich cathode material is 1.0-4.0 m². 2 / g. Compared to lithium-rich cathode materials with high specific surface area, the primary particles in lithium-rich cathode materials with low specific surface area O2 main phase, as mentioned earlier, have a larger particle size, thus the secondary particles, i.e., the lithium-rich cathode material, possess higher structural strength. When used in lithium-ion batteries, it can withstand higher rolling pressure, thereby achieving a compaction density of not less than 2.7 g / cm³ under 3.0T pressure. 3 The electrode plates effectively improve the energy density of lithium-ion batteries.

[0060] Furthermore, the aforementioned low specific surface area O2 main phase lithium-rich cathode material has a small contact area with the electrolyte, which can effectively alleviate the side reactions between the lithium-rich cathode material and the electrolyte during the charging-discharging process, thus exhibiting high cycle stability.

[0061] Furthermore, the median particle size of the aforementioned lithium-rich cathode material is 3.0-12.0 μm.

[0062] Furthermore, the tap density of the lithium-rich cathode material is 2.0-3.0 g / cm³. 3 .

[0063] Furthermore, the surface CO3 of the lithium-rich cathode material2- The content is 0.01wt%-0.5wt%, OH - The content is 0.01wt%-0.25wt%, Na + Content less than 0.005 wt%.

[0064] Based on the same inventive concept, this application also provides a method for preparing a lithium-rich cathode material, which includes, please refer to... Figure 1 :

[0065] Step 101: Under conditions of pH not lower than 7.5 and temperature of 50-70℃, the salt solution, alkaline solution and complexing agent undergo a co-precipitation reaction to generate a precursor with a particle size distribution SPAN of 1.2-1.8.

[0066] The molar ratio of nickel ions to manganese ions in the salt solution corresponds to the stoichiometric ratio of nickel to manganese in the lithium-rich cathode material. The particle size distribution SPAN is obtained according to the following formula:

[0067] This particle size refers to the volumetric particle size distribution.

[0068] The solutes in the above salt solution include NiSO4 and MnSO4. Among them, the metal ions in the salt solution (Ni...) + Mn 2+ The concentration is 1-2 mol / L.

[0069] The solute in the above-mentioned alkaline solution includes at least one of NaOH, Na₂CO₃, and NaHCO₃. The concentration of sodium ions in the alkaline solution is 1-2 mol / L.

[0070] The complexing agent is selected from at least one of the following: ammonia, ammonium sulfate, ammonium carbonate, ammonium bicarbonate, ammonium oxalate, ascorbic acid, and sodium dodecyl sulfate.

[0071] The complexing agent described above can be added to the reaction equipment in dry form or in the form of a complexing agent solution. It is preferred to add it to the reaction equipment in the form of a complexing agent solution so that the complexing agent can be dispersed more quickly in the reaction equipment along with the solvent. In this case, the concentration of the complexing agent in the complexing agent solution is 0.02-0.2 mol / L.

[0072] The reaction equipment for coprecipitation reactions can be a reaction vessel. Therefore, during a coprecipitation reaction, the salt solution, alkali solution, and complexing agent solution can be simultaneously pumped into the reaction vessel to maintain the pH of 7.5-11.0, the reaction temperature of 55-70℃, and the stirring rate of 400-800 rpm.

[0073] Furthermore, the nucleation and growth of crystals during the coprecipitation reaction are closely related to the pH environment of the reaction system. When the pH is high, for example, 11.5, nucleation is dominant in the reaction system. During this stage, crystal growth is slow, the particle size increases slowly, but the number of crystals increases significantly. When the pH is low, for example, 7.0, growth is dominant in the reaction system. During this stage, the particle size of the crystal phase increases rapidly, but only a very small number of crystal phases nucleate. In summary, the pH value at which nucleation is dominant in the reaction system is higher than the pH value of the reaction system. The overall trend is that nucleation occurs in a high pH environment, growth occurs in a lower pH environment, and then growth continues in a higher pH environment, with an overall trend of increasing SPAN. Therefore, in one embodiment of this application, the salt solution, alkaline solution, and complexing agent are first subjected to a coprecipitation reaction at a high pH value (greater than 9.0, for example, 11.5) for 1-5 hours, so that the particles in the reaction system nucleate to the nucleation particle size. Then, the pH of the reaction system is lowered by 0.5-1.5, allowing the salt solution, alkaline solution, and complexing agent to generate intermediate precursors with an intermediate median particle size under conditions conducive to growth at pH 7.5-11.0, resulting in an intermediate slurry. Next, the pH of the intermediate slurry is slightly increased, with the increase not exceeding 1 (e.g., 0.25, 0.5), to make the reaction system of the intermediate slurry more acidic or alkaline for crystal nucleation, thereby promoting an increase in the number of nuclei in the reaction system. The difference between the median particle size of the intermediate precursor in the reaction slurry and that before pH adjustment does not exceed ±0.3 μm, i.e., the change in median particle size of the intermediate precursor in the intermediate slurry does not exceed 0.6 μm. This aims to achieve a target precursor size with a relatively small difference and to increase the particle size distribution (SPAN) of the reaction product, resulting in a target precursor with a SPAN of 1.2-1.8.

[0074] Step 102: Perform multi-stage sintering on the first mixture including the precursor and sodium salt to obtain a sodium-containing precursor.

[0075] In the multi-stage sintering process, the sintering temperature increases sequentially, and the temperature of the first stage of the multi-stage sintering process is 400-600℃, and the sintering time of the first stage is 3-8 hours, so as to ensure that carbon and hydrogen elements escape in the form of CO2 and H2O(g) respectively in the first stage of sintering process, and avoid the generation of gas in the subsequent sintering process from affecting the phase formation process of sodium-containing precursors.

[0076] In the above multi-stage sintering process, the sintering temperature of the last stage can be 800-950℃.

[0077] During the multi-segment sintering process, the temperature can be continuously increased between "segments", or the temperature can be decreased (to room temperature) and then increased. The heating rate can be 2-5℃ / min.

[0078] In one embodiment of this application, the multi-stage sintering process is a two-stage sintering process. The temperature of the first stage sintering process is 400-600℃ and the sintering time is 3-8h; the temperature of the second stage sintering process is 800-950℃ and the sintering time is 10-20h.

[0079] Furthermore, the aforementioned sodium-containing precursor is actually a pure-phase P2-phase sodium-ion material prepared by heat exchange with lithium ions in step 103. Because during heat exchange with lithium ions in the lithium salt, some lithium ions will replace the sodium layer upon entering the P2-phase sodium-containing precursor, in one embodiment of this application, the molar ratio of sodium to nickel and manganese in the sodium-containing precursor is made consistent with the molar ratio of lithium content (mol) occupying the lithium layer in the lithium-rich cathode material to nickel and manganese. That is, in the first mixture, the molar ratio between sodium and the sum of nickel and manganese in the precursor satisfies the following relationship:

[0080] Furthermore, the first mixture also includes a dopant, which may be selected from at least one of the following: Ta source, Ti source, W source, Fe source, Sb source, Sn source, Ce source, Zn source, Mg source, K source, P source, S source, and F source.

[0081] The Ta source can be Ta₂O₅. The Nb source can be Nb₂O₅. The W source is WO₃. The Ti source can be TiO₂. The Fe source can be FePO₄ and / or Fe₂O₃. The Sb source can be Sb₂O₃ and / or Sb₂O₅. The Sn source can be SnO₂. The Ce source can be CeO₂ and / or CeF₃. The Al source can be Al₂O₃ and / or Al(OH)₃. The Si source can be SiO₂. The Co source can be Co₃O₄ and / or Co(OH)₂. The Zn source can be ZnO, and the Mg source can be MgO and / or Mg(OH)₂. The K source can be KOH and / or K₂S.

[0082] The phosphorus source can be at least one of NH4H2PO4, Li3PO4, H3PO4, and FePO4. The sulfur source can be Na2S and / or K2S. The sulfur source can be NaF, LiF, KF, NH4F, and / or CeF3.

[0083] Step 103: Sinter the second mixture, which includes a sodium-containing precursor and a lithium source, at 350-500°C for 5-20 hours to obtain a lithium-rich cathode material.

[0084] The heating rate is 2-5℃ / min.

[0085] The lithium source is selected from at least one of lithium carbonate, lithium hydroxide, lithium chloride, and lithium nitrate.

[0086] When the lithium source and the sodium-containing precursor are sintered together at 350-500℃, some lithium ions exchange with the alkali metal layer in the sodium-containing precursor, replacing the sodium layer in the sodium-containing precursor, while a small portion of lithium ions enter the transition metal layer.

[0087] Furthermore, to prevent lithium volatilization at high temperatures, the lithium element in the second mixture is in excess by 2-5 mol% compared to the designed value in the lithium-rich cathode material; that is, the molar ratio between the sum of nickel and manganese elements in the sodium-containing precursor is... Preferably,

[0088] Furthermore, the lithium-rich cathode material contains doping elements corresponding to the dopants in the first mixture; and for the lithium-rich cathode material, the doping elements can improve the structural stability, crystal strength, electrolyte tolerance, and high voltage tolerance of the lithium-rich cathode material to varying degrees.

[0089] Furthermore, a phase transition occurs during ion exchange, allowing some metal ions to re-occupy sites, thereby achieving low-temperature doping and partial coating effects. Therefore, in one embodiment of this application, the second mixture may further include a dopant, which may be selected from at least one of the following: Ta source, Ti source, W source, Fe source, Sb source, Sn source, Ce source, Zn source, Mg source, K source, P source, S source, and F source. This dopant may be the same as or different from the dopant in the second mixture.

[0090] The Ta source can be Ta₂O₅. The Nb source can be Nb₂O₅. The W source is WO₃. The Ti source can be TiO₂. The Fe source can be FePO₄ and / or Fe₂O₃. The Sb source can be Sb₂O₃ and / or Sb₂O₅. The Sn source can be SnO₂. The Ce source can be CeO₂ and / or CeF₃. The Al source can be Al₂O₃ and / or Al(OH)₃. The Si source can be SiO₂. The Co source can be Co₃O₄ and / or Co(OH)₂. The Zn source can be ZnO, and the Mg source can be MgO and / or Mg(OH)₂. The K source can be KOH and / or K₂S.

[0091] Specifically, when the doping elements of lithium-rich cathode materials include one or more of Ta, Nb, W, Ti, Fe, Sb, Sn, Ce, Al, Si, and Zn, the electrochemical inertness exhibited by the aforementioned doping elements during the charge-discharge process can play a role in supporting the local structure, suppressing the cell "breathing" effect, reducing lattice stress, and improving the stability of lithium-rich cathode materials.

[0092] When Co is included as a doping element in lithium-rich cathode materials, the capacity of the lithium-rich cathode materials can be improved.

[0093] When the doping elements of lithium-rich cathode materials include at least one of Mg, Na, and K, these elements, located in the alkali metal layer, can support the alkali metal layer during charge-discharge processes. This prevents lattice collapse and dislocation caused by excessive Li insertion / extraction, thus avoiding irreversible lithium ion extraction (i.e., difficulty in insertion) and the resulting rapid capacity decay. Furthermore, Mg, Na, and K can increase the interlayer spacing between alkali metal layers, thereby improving the lithium ion migration coefficient in the alkali metal layer and enhancing the kinetic performance of the lithium-rich cathode material, such as rate performance.

[0094] When the doping element of lithium-rich cathode material includes P, local PO4 can be formed in the lithium-rich submaterial. 3- Polyanionic structure, local PO4 3- The polyanionic structure can form stronger covalent bonds with cations, thus effectively improving the high voltage tolerance of lithium-rich cathode materials.

[0095] When the doping elements of lithium-rich cathode materials include S and / or F, S and F will be doped at the O anion sites. S and F can form covalent bonds with transition metals that are stronger than TM-O (TM represents transition metal), thus effectively improving the structural stability of the material.

[0096] When the doping elements of lithium-rich cathode materials include W, Sb, and Co, W, Sb, and Co can be enriched at the grain boundaries or partially melted into the original crystal structure to eliminate grain boundaries and reduce the specific surface area of ​​the material. This inhibits the intrusion of electrolyte into the lithium-rich cathode material during the charging-discharging process, thereby reducing the side reactions between the electrolyte and the lithium-rich cathode material.

[0097] When the doping elements of lithium-rich cathode materials include Ti and Al, some Ti and Al react chemically with oxygen and lithium source on the surface of the lithium-rich cathode material to generate TiO2, Li2TiO3, and Li4Ti5O. 12 Inert substances such as Al2O3 and LiAlO2, fast ion conductors, or a composite structure of the two can be used to improve the surface tolerance and lithium-ion transport performance of lithium-rich cathode materials.

[0098] It is worth noting that in existing technologies, lithium-rich cathode materials with O2 phase as the main phase are obtained by replacing sodium in a lithium-sodium composite precursor with lithium ions using a molten salt exchange method at a temperature of approximately 280℃ (not exceeding 300℃). This method suffers from the problem of excessive lithium salt usage, i.e., low raw material utilization. More importantly, the ion exchange system formed by a large amount of lithium molten salt is prone to agglomeration and wall adhesion after cooling to room temperature, which necessitates the forced stripping of the prepared cathode material from the reactor, resulting in low yield. In contrast, the preparation method provided in steps 101-103 above significantly increases the thermodynamic driving force of Li-Na ion exchange due to the high sintering temperature, while reducing the kinetic driving force formed by the ion concentration difference in the sodium-containing precursor and the single lithium salt. The actual exchange effect is no less than that of the low-temperature molten salt ion exchange system (based on the residual Na content in the final system). Furthermore, in the existing technology, when preparing lithium-rich cathode materials with O2 phase as the main phase by low-temperature molten salt exchange method, residual alkali is easily generated on the surface of the lithium-ion cathode material synthesized under low-temperature conditions. Therefore, more lithium needs to be added to avoid lithium capture when residual alkali is generated on the surface, which leads to the problem of insufficient lithium in the layered structure of the lithium-rich cathode material.

[0099] Based on the same inventive concept, this application also provides a lithium-ion battery, wherein the positive electrode sheet of the lithium-ion battery has a compaction density of not less than 2.7 g / cm³ on the side opposite to the negative electrode sheet. 3 The mixed slurry (under 3.0T pressure) is prepared by mixing the aforementioned positive electrode material with O2 phase as the main phase, as well as conductive agent and binder.

[0100] The following detailed description is provided through Examples 1-20 and Comparative Examples 1-4.

[0101] Example 1

[0102] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 7.5. Maintain the stirring speed at 500 rpm and the reaction temperature at 60°C until the precipitate reaches the specified particle size D. 50 =10.0μm.

[0103] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 2 mol / L; the molar ratio of nickel to manganese is 0.30 / 0.45. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 2 mol / L; the complexing agent is an ammonia solution, and the total concentration of solute molecules is 0.1 mol / L.

[0104] S2, pH increased by 0.2, maintaining the reaction precipitate D 50The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0105] S3. With a total molar ratio of sodium to nickel and manganese transition metal elements of 0.8*1.03 (Na excess 3%), sodium carbonate and transition metal salt precursor A are thoroughly mixed. After mixing, the mixture is placed in an air atmosphere kiln for sintering. Two-stage sintering is adopted, with continuous heating between the two stages. The first stage sintering temperature is 550℃ and the sintering time is 4h. The second stage sintering temperature is 860℃ and the sintering time is 10h. The heating rate throughout is 2℃ / min. After the two-stage sintering is completed, the mixture is naturally cooled to room temperature to obtain layered Na ion cathode compound C.

[0106] S4. With a lithium / (nickel + manganese) molar ratio of 1.01*(1.05 / 0.75), i.e., lithium excess of 1 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was sintered in an air atmosphere furnace at a sintering temperature of 380℃ for 10 hours at a heating rate of 2℃ / min. After sintering, it was allowed to cool naturally to room temperature. Residual Na was then washed with deionized water, centrifuged, and dried in a 140℃ oven for 16 hours to obtain the target lithium-rich cathode product with O2 as the main phase. The SEM image of this lithium-rich cathode target product can be found in [reference needed]. Figure 3 .

[0107] Example 2

[0108] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 2 hours at pH 11.5. Lower the pH of the reactor to maintain it at 10.8. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =7.0μm.

[0109] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 2 mol / L; the molar ratio of nickel to manganese is 0.24 / 0.54. The alkaline solution is NaOH solution, containing Na... + The total concentration is 2 mol / L; the complexing agent solution is sodium dodecyl sulfate solution with a total solute molecule concentration of 0.1 mol / L.

[0110] S2 and pH are increased by 0.2, while maintaining the D50 fluctuation value within ±0.3, so that the SPAN of the reaction precipitate is 1.3 ± 0.1. The reaction continues until the theoretical dry material weight reaches 10 kg, at which point the feed is stopped, and the product is aged, washed, and dried to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0111] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metals of 0.65*1.05 (Na excess 5%). After mixing, the mixture was placed in an air atmosphere furnace for sintering. Two-stage sintering was adopted, with continuous heating between the two stages. The first stage sintering temperature was 600℃ and the sintering time was 4 hours. The second stage sintering temperature was 900℃ and the sintering time was 10 hours. The heating rate was 2℃ / min throughout. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0112] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.87 / 0.78), i.e. lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for sintering at a sintering temperature of 400℃ for 10 h at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, the residual Na was washed with deionized water. After washing, the mixture was centrifuged and finally dried in an oven at 140℃ for 16 h to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0113] Example 3

[0114] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 8.5. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =12.0μm.

[0115] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.5 mol / L; the molar ratio of nickel to manganese is 0.30 / 0.45. The alkaline solution is a Na2C2O4 solution, containing Na... + The total concentration is 1.5 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0116] S2, pH increased by 0.2, D maintained 50The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0117] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.65*1.04 (Na excess 4%). After mixing, the mixture was placed in an air atmosphere kiln for sintering using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 570℃ and the sintering time was 4 hours. The second stage sintering temperature was 880℃ and the sintering time was 10 hours. The heating rate was 2℃ / min throughout the process. After the second stage sintering was completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0118] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.90 / 0.75), i.e. lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was then sintered in an air atmosphere furnace at a sintering temperature of 430℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. The residual Na was then washed with deionized water, centrifuged, and finally dried in a 140℃ oven for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0119] Example 4

[0120] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction at pH 8.9 for 4 hours. Lower the pH of the reactor to maintain it at 7.9. Maintain the stirring speed at 600 rpm and the reaction temperature at 70°C until the precursor precipitate reaches the specified particle size D. 50 =10.5μm.

[0121] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L. The molar ratio of nickel to manganese is 0.24 / 0.54. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the complexing agent solution is an ammonium oxalate solution with a total solute molecule concentration of 0.08 mol / L.

[0122] S2, pH increased by 0.2, D maintained 50The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0123] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.8*1.05 (Na excess 5%). After mixing, the mixture was placed in an air atmosphere furnace for sintering using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5 hours, while the second stage sintering temperature was 900℃ and the sintering time was 10 hours. The heating rate was 2℃ / min throughout the process. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0124] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(1.02 / 0.78), i.e. lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for sintering at a sintering temperature of 400℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, the residual Na was washed with deionized water. After washing, the mixture was centrifuged and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0125] Example 5

[0126] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 4 hours at pH 9.3. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0127] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.27 / 0.48. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0128] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0129] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%). After mixing, the mixture was placed in an air atmosphere furnace for sintering using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5 hours. The second stage sintering temperature was 880℃ and the sintering time was 12 hours. The heating rate was 2℃ / min throughout the process. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0130] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.75), i.e. lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. After mixing, the mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, the residual Na was washed with deionized water, centrifuged after washing, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0131] Example 6

[0132] S1. The salt solution, alkali solution, and complexing agent solution are simultaneously pumped into the reactor for co-precipitation. The pH of the reactor is maintained at 8.0, the stirring speed is 600 rpm, and the reaction temperature is 70℃. The reaction proceeds until the precursor precipitate reaches the specified particle size D. 50 =10.0μm.

[0133] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.5 mol / L; the molar ratio of nickel to manganese is 0.30 / 0.48. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.5 mol / L; the solute in the complexing agent solution is ammonium sulfate, and the total concentration of solute molecules is 0.1 mol / L.

[0134] S2, pH increased by 0.2 to maintain D 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.4±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0135] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.03 (Na excess 3%). After mixing, the mixture was placed in an air atmosphere kiln for sintering. Two-stage sintering was adopted, with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5h. The second stage sintering temperature was 900℃ and the sintering time was 10h. The heating rate throughout was 2℃ / min. After the two-stage sintering was completed, the mixture was naturally cooled to room temperature to obtain layered Na ion cathode compound C.

[0136] S4. With a lithium / (nickel + manganese) molar ratio of 1.01*(0.95 / 0.78), i.e., lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 12 hours at a heating rate of 2℃ / min. After sintering, it was allowed to cool naturally to room temperature. Then, the residual Na was washed with deionized water, centrifuged after washing, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0137] Example 7

[0138] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0139] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0140] S2 and pH are increased by 0.2, and the D50 fluctuation value is kept within ±0.3. The SPAN of the reaction precipitate is 1.4±0.1. The reaction continues until the theoretical dry material weight reaches 10Kg, then the feeding is stopped. After aging, washing and drying, the secondary sphere precursor is obtained; namely, nickel-manganese composite transition metal salt precursor A.

[0141] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%). After mixing, the mixture was placed in an air atmosphere kiln for sintering. Two-stage sintering was adopted, with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5h. The second stage sintering temperature was 880℃ and the sintering time was 12h. The heating rate throughout was 2℃ / min. After the two-stage sintering was completed, the mixture was naturally cooled to room temperature to obtain layered Na ion cathode compound C.

[0142] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate and corresponding molar amounts of Nb and Ti sources. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 10 hours at a heating rate of 2℃ / min. After sintering, it was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of O2-type lithium-rich cathode.

[0143] Example 8

[0144] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0145] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0146] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.6±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0147] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%). After mixing, the mixture was placed in an air atmosphere kiln for sintering. Two-stage sintering was adopted, with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5h. The second stage sintering temperature was 880℃ and the sintering time was 12h. The heating rate throughout was 2℃ / min. After the two-stage sintering was completed, the mixture was naturally cooled to room temperature to obtain layered Na ion cathode compound C.

[0148] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, while mixing the layered Na ion cathode compound C with lithium carbonate, the corresponding molar amounts of Ta, Sb, and Al sources are also thoroughly mixed. The mixture is placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 350℃ for 10 hours at a heating rate of 2℃ / min. After sintering, it is naturally cooled to room temperature, and then the residual Na is washed with deionized water. After washing, it is centrifuged and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0149] Example 9

[0150] S1. Simultaneously pump the salt solution, alkaline solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0151] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0152] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.5±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0153] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%). The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5 hours. The second stage sintering temperature was 880℃ and the sintering time was 12 hours. The heating rate was 2℃ / min throughout the process. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0154] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C is thoroughly mixed with lithium carbonate and corresponding molar amounts of W source, Fe source, and Na source. The mixture is placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 10 hours at a heating rate of 2℃ / min. After sintering, it is allowed to cool naturally to room temperature. Then, residual Na is washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0155] Example 10

[0156] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm,

[0157] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L. The solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0158] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.6±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0159] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%). The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5 hours. The second stage sintering temperature was 880℃ and the sintering time was 12 hours. The heating rate was 2℃ / min throughout the process. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0160] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na ion cathode compound C is thoroughly mixed with lithium carbonate and corresponding molar amounts of Sn, Co, and Zn sources. The mixture is then placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture is allowed to cool naturally to room temperature. The residual Na is then washed with deionized water, centrifuged, and finally dried in a 140℃ oven for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0161] Example 11

[0162] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0163] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0164] S2, pH increased by 0.2 to maintain D 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.7±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0165] S3. Sodium carbonate and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%). The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 500℃ and the sintering time was 5 hours. The second stage sintering temperature was 880℃ and the sintering time was 12 hours. The heating rate was 2℃ / min throughout the process. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0166] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate and corresponding molar amounts of Ce and Mg sources. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 10 hours at a heating rate of 2℃ / min. After sintering, it was allowed to cool naturally to room temperature. Then, the residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of O2-type lithium-rich cathode.

[0167] Example 12

[0168] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 8.0. Maintain the stirring speed at 600 rpm and the reaction temperature at 70°C. Continue the reaction until the precursor precipitate reaches the specified particle size D. 50 =10.0μm.

[0169] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.5 mol / L; the molar ratio of nickel to manganese is 0.29 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.5 mol / L. The solute in the complexing agent solution is ammonium sulfate, and the total concentration of solute molecules is 0.1 mol / L.

[0170] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.5±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0171] S3. With a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.03 (Na excess 3%), sodium carbonate and transition metal salt precursor A were mixed together, along with corresponding molar amounts of Nb, Si, and Al sources. The mixture was sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃, and the sintering time was 5 hours. The second stage sintering temperature was 900℃, and the sintering time was 10 hours. The overall heating rate was 2℃ / min. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0172] S4. With a lithium / (nickel + manganese) molar ratio of 1.01*(0.95 / 0.76), i.e. lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was then placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 12 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. The residual Na was then washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0173] Example 13

[0174] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor and carry out a co-precipitation reaction for 5 hours at a pH of 9.0. Then, lower the pH of the reactor to maintain a pH of 8.0. The stirring speed is 600 rpm and the reaction temperature is 70℃. Wait until the precursor of the reaction precipitate reaches the specified particle size D50 = 10.0 μm.

[0175] 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 1.5 mol / L; the molar ratio of nickel to manganese is 0.29 / 0.47. The alkaline solution is a Na2CO3 solution, and the Na in the alkaline solution... + The total concentration is 1.5 mol / L. The solute in the complexing agent solution is ammonium sulfate, and the total concentration of solute molecules is 0.1 mol / L.

[0176] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.7±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0177] S3. With a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.03 (Na excess 3%), sodium carbonate and transition metal salt precursor A were mixed, along with corresponding molar amounts of W source, Al source, and Na source. The mixture was sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃, and the sintering time was 5 hours. The second stage sintering temperature was 900℃, and the sintering time was 10 hours. The overall heating rate was 2℃ / min. After the two stages of sintering were completed, the mixture was allowed to cool naturally to room temperature to obtain layered Na ion cathode compound C.

[0178] S4. With a lithium / (nickel + manganese) molar ratio of 1.01*(0.95 / 0.76), i.e. lithium excess of 2 mol%, the layered Na ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was then placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 12 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. The residual Na was then washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0179] Example 14

[0180] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 2 hours at pH 9.3. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0181] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L. The solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0182] S2, pH increased by 0.2 to maintain D 50 The fluctuation value should not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.6 ± 0.1. The reaction continues until the theoretical dry material weight reaches 10 kg, then the feeding is stopped, and the product is aged, washed, and dried to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A. The molar ratio of nickel to manganese is 0.26 / 0.47.

[0183] S3. Using a total molar ratio of sodium to nickel and manganese transition metals of 0.73*1.05 (Na excess 5%), sodium carbonate and transition metal salt precursor A were mixed, along with corresponding molar amounts of Ta, Ce, Al, and Na sources. The mixture was sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 880℃ for 12 hours, with a total heating rate of 2℃ / min. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na-ion cathode compound C.

[0184] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 410℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0185] Example 15

[0186] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 2 hours at pH 9.3. Lower the pH of the reactor to maintain a pH of 8.3, stirring at 600 rpm and at a reaction temperature of 65°C. Continue the reaction until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0187] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0188] S2, pH increased by 0.2 to maintain D 50 The fluctuation value should not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.7-1.8. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0189] S3. With a total molar ratio of sodium to nickel and manganese transition metal elements of 0.73*1.05 (Na excess 5%), sodium carbonate and composite transition metal salt precursor A are mixed, and corresponding molar amounts of Nb source, Ti source, Ce source and Mg source are also fully mixed. The mixture is placed in an air atmosphere kiln for sintering, using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature is 500℃ and the sintering time is 5h. The second stage sintering temperature is 880℃ and the sintering time is 12h. The heating rate throughout is 2℃ / min. After the two stages of sintering are completed, the mixture is naturally cooled to room temperature to obtain layered Na ion cathode compound C.

[0190] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 410℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0191] Example 16

[0192] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 8.0. Maintain the stirring speed at 600 rpm and the reaction temperature at 70°C. Continue the reaction until the precursor precipitate reaches the specified particle size D. 50 =10.0μm.

[0193] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.5 mol / L; the molar ratio of nickel to manganese is 0.29 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.5 mol / L. The solute in the complexing agent solution is ammonium sulfate, and the total concentration of solute molecules is 0.1 mol / L.

[0194] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0195] S3. Using a total molar ratio of sodium to nickel / manganese transition metal elements of 0.73*1.03 (Na excess 3%), sodium carbonate and transition metal salt precursor A were mixed, along with the doping sources Ta, Al, Co, and K. The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 900℃ for 10 hours, with a total heating rate of 2℃ / min. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na-ion cathode compound C.

[0196] S4. With a lithium / (nickel + manganese) molar ratio of 1.01*(0.95 / 0.76), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 12 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0197] Example 17

[0198] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 8.0. Maintain the stirring speed at 600 rpm and the reaction temperature at 70°C. Continue the reaction until the precursor precipitate reaches the specified particle size D. 50 =10.0μm.

[0199] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.5 mol / L; the alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.5 mol / L; the solute in the complexing agent solution is ammonium sulfate, and the total concentration of solute molecules is 0.1 mol / L.

[0200] S2, pH increased by 0.2 to maintain D 50 The fluctuation value should not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.7 ± 0.1. The reaction continues until the theoretical dry material weight reaches 10 kg, then the feeding is stopped, and the product is aged, washed, and dried to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A. The molar ratio of nickel to manganese is 0.29 / 0.47.

[0201] S3. Using a total molar ratio of sodium to nickel / manganese transition metal elements of 0.73*1.03 (Na excess 3%), sodium carbonate and transition metal salt precursor A were mixed, along with the doping sources: Nb, Sn, Al, and Na. The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 900℃ for 10 hours, with a total heating rate of 2℃ / min. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na-ion cathode compound C.

[0202] S4. With a lithium / (nickel + manganese) molar ratio of 1.01*(0.95 / 0.76), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 400℃ for 12 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0203] Example 18

[0204] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor and carry out a co-precipitation reaction for 3 hours at a pH of 9.8. Then, lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0205] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L; the solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0206] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.4±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0207] S3. Using a total molar ratio of sodium to nickel and manganese transition metals of 0.73*1.05 (Na excess 5%), sodium carbonate and transition metal salt precursor A were mixed, along with molar amounts of Ta, Ce, Al, Na, P, and F sources. The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 880℃ for 12 hours, with a total heating rate of 2℃ / min. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na-ion cathode compound C.

[0208] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 410℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0209] Example 19

[0210] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0211] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L. The solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0212] S2, pH increased by 0.2 to maintain D 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0213] S3. Using a total molar ratio of sodium to nickel / manganese transition metal elements of 0.73*1.05 (Na excess 5%), sodium carbonate and transition metal salt precursor A were mixed, along with corresponding molar amounts of Ta, Ce, Al, Na, S, and F sources. The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 880℃ for 12 hours, with a total heating rate of 2℃ / min. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na-ion cathode compound C.

[0214] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 410℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0215] Example 20

[0216] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 3 hours at pH 9.8. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0217] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.26 / 0.47. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L. The solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0218] S2, pH increased by 0.3, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; namely, nickel-manganese composite transition metal salt precursor A.

[0219] S3. Using a total molar ratio of sodium to nickel / manganese transition metal elements of 0.73*1.05 (Na excess 5%), sodium carbonate and the composite transition metal salt precursor A were mixed, along with corresponding molar amounts of Ta, Ce, Al, Na, S, and P sources. The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 880℃ for 12 hours, with a total heating rate of 2℃ / min. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na-ion cathode compound C.

[0220] S4. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.73), i.e., lithium excess of 2 mol%, the layered Na-ion cathode compound C was thoroughly mixed with lithium carbonate. The mixture was placed in an air atmosphere furnace for secondary sintering at a sintering temperature of 410℃ for 10 hours at a heating rate of 2℃ / min. After sintering, the mixture was allowed to cool naturally to room temperature. Then, residual Na was washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 hours to obtain the target product of lithium-rich cathode with O2 as the main phase.

[0221] Comparative Example 1

[0222] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 7.5. Maintain the stirring speed at 500 rpm and the reaction temperature at 60°C until the precursor precipitate reaches the specified particle size D. 50 =10.0μm.

[0223] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 2 mol / L. The molar ratio of nickel to manganese is 0.30 / 0.45. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 2 mol / L. The complexing agent is an aqueous ammonia solution, and the total concentration of solute molecules is 0.1 mol / L.

[0224] S2, pH increased by 0.2 to maintain D 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. The reaction continues until the theoretical dry material weight reaches 10Kg, then the feeding is stopped, and the product is aged, washed, and dried to obtain the secondary sphere precursor; that is, the nickel-manganese composite transition metal salt precursor.

[0225] S3. With a lithium / (nickel + manganese) molar ratio of 1.01*(1.05 / 0.75), i.e., lithium in excess by 1 mol%, the transition metal salt precursor and lithium carbonate were thoroughly mixed. After mixing, the mixture was placed in an air atmosphere furnace for sintering using a two-stage sintering method, with continuous heating between the two stages. The first stage sintering temperature was 550℃, and the sintering time was 4 hours. The second stage sintering temperature was 860℃, and the sintering time was 10 hours. The overall heating rate was 2℃ / min. After the second stage sintering, the mixture was allowed to cool naturally to room temperature, then washed with deionized water. After washing, the mixture was centrifuged and dried in a 140℃ oven for 16 hours to obtain the O3-type lithium-rich cathode target product. The SEM image of this lithium-rich cathode target product can be found in the reference image. Figure 6 .

[0226] Comparative Example 2

[0227] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 2 hours at pH 11.5. Lower the pH of the reactor to maintain it at 10.8. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =7.0μm.

[0228] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 2 mol / L; the molar ratio of nickel to manganese is 0.24 / 0.54. The alkaline solution is NaOH solution, containing Na... + The total concentration is 2 mol / L. The solute in the complexing agent solution is sodium dodecyl sulfate solution, and the total concentration of solute molecules is 0.1 mol / L.

[0229] S2, pH increased by 0.3 to maintain D 50 The fluctuation value should not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material weight reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor.

[0230] S3. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.87 / 0.78), i.e., lithium excess of 2 mol%, the transition metal salt precursor and lithium carbonate were thoroughly mixed. After mixing, the mixture was placed in an air atmosphere furnace for sintering. Two-stage sintering was adopted, with continuous heating between the two stages. The first stage sintering temperature was 600℃ and the sintering time was 4 hours. The second stage sintering temperature was 900℃ and the sintering time was 10 hours. The heating rate throughout was 2℃ / min. After the second stage sintering was completed, the mixture was naturally cooled to room temperature. Then, it was washed with deionized water. After washing, it was centrifuged and finally dried in an oven at 140℃ for 16 hours to obtain a conventional O3 type lithium-rich cathode.

[0231] Comparative Example 3

[0232] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 5 hours at pH 9.0. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0233] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.27 / 0.48. The alkaline solution is a Na2CO3 solution, containing Na... + The total concentration is 1.0 mol / L. The solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0234] S2 and pH are increased by 0.2 to keep the D50 fluctuation value not exceeding ±0.3. The reaction continues until the theoretical dry material weight reaches 10Kg, then the feeding is stopped. The particle size SPAN = 1.3±0.1. After aging, washing, and drying, the secondary spherical precursor is obtained; that is, the nickel-manganese composite transition metal salt precursor.

[0235] S3. With a lithium / (nickel + manganese) molar ratio of 1.02*(0.98 / 0.75), i.e., lithium in excess of 2 mol%, after thorough mixing, the mixture of transition metal salt precursor and lithium carbonate is placed in an air atmosphere furnace for sintering. Two-stage sintering is adopted, with continuous heating between the two stages. The first stage sintering temperature is 500℃ and the sintering time is 5h. The second stage sintering temperature is 880℃ and the sintering time is 12h. The heating rate throughout is 2℃ / min. After the second stage sintering is completed, the mixture is naturally cooled to room temperature. Then, it is washed with deionized water, centrifuged after washing, and finally dried in an oven at 140℃ for 16h to obtain the O3 type lithium-rich cathode target product.

[0236] Comparative Example 4

[0237] S1. Simultaneously pump the salt solution, alkali solution, and complexing agent solution into the reactor. Perform a co-precipitation reaction for 4 hours at pH 9.3. Lower the pH of the reactor to maintain it at 8.3. Maintain the stirring speed at 600 rpm and the reaction temperature at 65°C until the precursor precipitate reaches the specified particle size D. 50 =9.5μm.

[0238] The salt solution contains NiSO4 and MnSO4 salts, respectively, with a total metal ion concentration of 1.0 mol / L; the molar ratio of nickel to manganese is 0.27 / 0.48. The alkaline solution is a Na2CO3 solution, containing Na...+ The total concentration is 1.0 mol / L. The solute in the complexing agent solution is ammonium oxalate, and the total concentration of solute molecules is 0.08 mol / L.

[0239] S2, pH increased by 0.2, D maintained 50 The fluctuation value does not exceed ±0.3, so that the SPAN of the reaction precipitate is 1.3±0.1. Continue the reaction until the theoretical dry material mass reaches 10Kg, then stop feeding, age, wash, and dry to obtain the secondary sphere precursor; that is, transition metal salt precursor A.

[0240] S3. Sodium carbonate, lithium carbonate, and transition metal salt precursor A were thoroughly mixed with a total molar ratio of sodium, lithium, and nickel / manganese transition metals of 0.73*1.05:0.25*1.02:0.75 (Na excess 5 mol%, Li excess 2 mol%). The mixture was then sintered in an air atmosphere furnace using a two-stage sintering method with continuous heating between the two stages. The first stage sintering temperature was 500℃ for 5 hours, and the second stage sintering temperature was 880℃ for 12 hours, with a heating rate of 2℃ / min throughout. After the two stages of sintering, the mixture was allowed to cool naturally to room temperature to obtain layered Na / Li composite ion cathode compound C.

[0241] S4. With a lithium total / (nickel + manganese) molar ratio of 5.0*(0.98 / 0.75), i.e., lithium excess of 400 mol%, the layered Na, Li composite ion cathode compound C was thoroughly mixed with lithium nitrate: lithium chloride = 88 wt%: 12 wt%. The mixture was placed in an air atmosphere furnace for ion exchange at a reaction temperature of 280℃ for 10 h at a heating rate of 2℃ / min. After the reaction was completed, it was allowed to cool naturally to room temperature. Then, residual Na and Li were washed with deionized water, centrifuged, and finally dried in an oven at 140℃ for 16 h to obtain the O2-type lithium-rich cathode product prepared by the traditional ion exchange method.

[0242] The specific surface area of ​​Examples 1-20 and Comparative Examples 1-4 was tested using nitrogen adsorption-desorption, and the residual sodium content in each bulk phase was tested using ICP.

[0243] Meanwhile, XRD patterns (i.e., XRD patterns) were also tested for Examples 1-20 and Comparative Examples 1-4. The XRD patterns for Examples 1, 8, and Comparative Example 1 are shown below. Figure 2 , Figure 4 , Figure 5 As shown, the XRD-related data for the other embodiments are shown in Table 1.

[0244] Further reference Figure 7It can be seen that the main phase of the lithium-rich cathode described in Examples 1 and 8 is O2 phase, and its (002) main peak is located between 2*theta = 18.3 and 18.5°, while the main peak of the conventional O3 type lithium-rich cathode described in Comparative Example 1 is located between 2*theta = 18.5 and 18.8°.

[0245] Table 1

[0246]

[0247]

[0248] Note: In the sample composition table, lithium in parentheses indicates the lithium content in the alkali metal layer, and lithium outside parentheses indicates the lithium content in the lithium layer.

[0249] The materials from Examples 1-20 and Comparative Examples 1-4 were mixed with PVDF binder and Super-P conductive agent to prepare a mixed slurry, which was then coated onto the positive electrode sheet with an areal density of 8-10 g / cm³. 2 The electrode compaction density is 2.85±0.3 g / cm³. 3 The positive electrode area is π*0.75*0.75cm. 2 A coin cell was fabricated. The capacity and initial coulombic efficiency of the coin cell were tested, and the capacity retention and voltage stability were tested at 2.5-4.55V, 0.1C, and 1.0C for 100 cycles. The discharge curves for the cycle tests of Examples 1, 8, and Comparative Example 1 are shown below. Figure 8 , Figure 9 , Figure 10 For specific test data, please refer to Table 2.

[0250] Table 2

[0251]

[0252] As shown in Table 2, the cycle performance, capacity, voltage decay performance and coulombic efficiency of the lithium-rich cathode materials with O2 phase as the main phase in Examples 1-20 were significantly improved.

[0253] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A lithium-rich cathode material, characterized in that, The general molecular formula of the lithium-rich cathode material is: Li x Ni a Mn b M c O 2- d M' d , 0.87≤x≤1.05, 0.75<a+b+c<0.78, 0.42≤a / b≤0.67, 0≤c≤0.02, 0≤d≤0.02, M is at least one of Ta, Nb, W, Ti, Fe, Sb, Sn, Ce, Al, Si, Co, Zn, Mg, and K, and M' is one or more of P, S, and F; wherein, In the XRD pattern of the lithium-rich cathode material, the main peak is the O2 phase, and the intensity ratio of the first main peak to the second main peak is 1.3-1.8; the diffraction angle of the main peak is 18.3°-18.5°, the diffraction angle of the first main peak is 44.3°-44.7°, and the diffraction angle of the second main peak is 36.6°-37°. The content of the O2 phase in the lithium-rich cathode material is not less than 80%. The intensity ratio of the second main peak to the main peak is 0.15-0.30; the full width at half maximum (FWHM) of the first main peak is... A ≥0.5°, the full width at half maximum (FWHM) of the second main peak B ≥0.4°.

2. The lithium-rich cathode material as described in claim 1, characterized in that, The specific surface area of ​​the lithium-rich cathode material is 1.0-4.0 m². 2 / g; the median particle size of the lithium-rich cathode material is 3.0-12.0μm.

3. The lithium-rich cathode material as described in claim 2, characterized in that, The lithium-rich cathode material has a compaction density of no less than 2.7 g / cm³ under a pressure of 3.0 T. 3 The tap density of the lithium-rich cathode material is 2.0-3.0 g / cm³. 3 .

4. The lithium-rich cathode material as described in claim 1 or 2, characterized in that, CO3 on the surface of the lithium-rich cathode material 2- The content is 0.01wt%-0.5wt%, OH - The content is 0.01wt%-0.25wt%, Na + The content is less than 0.005 wt%.

5. A method for preparing the lithium-rich cathode material as described in any one of claims 1-4, characterized in that, include: Under conditions of pH not lower than 7.5 and temperature of 50-70℃, a co-precipitation reaction is carried out with salt solution, alkaline solution and complexing agent to generate a precursor with a particle size distribution SPAN of 1.2-1.8; A first mixture comprising the precursor and sodium salt is subjected to a multi-stage sintering process to obtain a sodium-containing precursor; wherein the sintering temperature in the multi-stage sintering process increases sequentially, and the multi-stage sintering process consists of two stages: the temperature of the first stage sintering process is 400-600℃, and the sintering time of the first stage sintering process is 3-8 hours; the temperature of the second stage sintering process is 800-950℃, and the sintering time of the second stage sintering process is 10-20 hours; The second mixture, comprising the sodium-containing precursor and the lithium source, is sintered at 350-500°C for 5-20 hours to obtain the lithium-rich cathode material.

6. The method as described in claim 5, characterized in that, The process involves co-precipitating a salt solution, an alkaline solution, and a complexing agent under conditions of pH not lower than 7.5 and temperature of 50-70℃ to generate a target precursor with a particle size distribution (SPAN) of 1.2-1.8, comprising: The salt solution, the alkaline solution, and the complexing agent solution containing the complexing agent are subjected to a co-precipitation reaction under conditions of pH 7.5-11.0 to generate an intermediate precursor with an intermediate median particle size, thereby obtaining an intermediate slurry. The pH value of the intermediate slurry is increased so that the median particle size variation of the intermediate precursor in the intermediate slurry does not exceed 0.6 μm, thereby obtaining a target precursor with a particle size distribution SPAN of 1.2-1.8; wherein the difference between the pH value of the intermediate slurry after the increase and the pH value before the increase does not exceed 1.

7. The method as described in claim 5, characterized in that, In the first mixture, the molar ratio of sodium to the sum of nickel and manganese in the precursor satisfies the following relationship: 0.65 ≤ ≤0.

88.

8. The method as described in claim 5, characterized in that, The first mixture further includes at least one of the following sources: Ta source, Ti source, W source, Fe source, Sb source, Sn source, Ce source, Zn source, Mg source, K source, P source, S source, and F source.

9. The method as described in claim 5, characterized in that, The second mixture further includes at least one source selected from Ta, Ti, W, Fe, Sb, Sn, Ce, Zn, Mg, K, P, S, and F; in the second mixture, the molar ratio of lithium to the sum of nickel and manganese in the sodium-containing precursor is 1.

0. ≤ ≤1.05 .

10. The method according to any one of claims 5-9, characterized in that, After obtaining the lithium-rich cathode material, the process further includes: The lithium-rich cathode material was washed with water and centrifuged to obtain a water-containing lithium-rich cathode material. The aqueous lithium-rich cathode material is dried at 120-160℃.

11. A lithium-ion battery, characterized in that, include: The lithium-rich cathode material according to any one of claims 1-4, or the lithium-rich cathode material prepared by the method according to any one of claims 5-10.

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