A sodium ion precursor material with a double concentration gradient and a preparation method thereof

Abstract

The present invention provides a sodium ion precursor material with a double concentration gradient and a preparation method thereof. The chemical composition of the sodium ion battery material of the present invention is: Ni x Mn y Fe 0.9‑x‑y Cu z A 0.1‑z (OH) 2 , where 0.1 ≤ x ≤ 0.5, 0.3 ≤ y ≤ 0.5, 0.05 ≤ z ≤ 0.1, A is a doping element, and the sodium ion precursor material has a composite structure with a double concentration gradient distribution of manganese-iron and nickel-copper. The preparation method includes: First, prepare Ni, Mn, and Fe salt solutions; prepare an additive solution of Cu and A; prepare a sodium hydroxide or sodium carbonate solution as a precipitant; prepare ammonia water as a complexing agent; Second, introduce a protective atmosphere into the reaction system, and put the metal salt solution, precipitant, complexing agent, and additive into the autoclave for coprecipitation reaction; Third, filter, wash, and dry the synthesis product in step two to obtain a nickel-iron-manganese-based hydroxide precursor with a double concentration gradient.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical material preparation, and relates to the preparation of sodium ion battery precursor materials, and more specifically, to a method for preparing a dual-concentration gradient precursor material. Background Art

[0002] With the rapid development of renewable energy and smart grids, higher requirements are placed on efficient and economical energy storage systems. Lithium-ion batteries have been widely used in portable electronic devices due to their high energy density, high efficiency and light weight, but limited lithium resources and expensive lithium costs restrict their further development.

[0003] Due to the high natural abundance of sodium and similar chemical properties to lithium, sodium-ion batteries are considered to be a low-cost alternative to lithium-ion batteries and are expected to be used in the future low-speed electric vehicles and energy storage markets. The primary challenge in the development of sodium-ion batteries is to develop high-performance and low-cost electrode materials. Different types of precursor materials have been studied in sodium-ion batteries (SIBs), among which layered metal oxides with simple synthesis routes have shown great potential.

[0004] Among the existing sodium ion cathode materials, layered oxides, especially manganese-rich sodium oxide (NaxMnO 2 ) is considered to be one of the most attractive precursor candidate materials due to its high specific capacity and cost-effectiveness. However, under high voltage conditions (such as above 4.0V), irreversible phase changes and structural distortions and cation rearrangements caused by anion redox reactions will lead to slow sodium ion kinetics and severe battery capacity decay. It is worth noting that the ion transport kinetics depends largely on the main structure and ion diffusion channels of the electrode material. A stable main structure can avoid the collapse of the lattice and diffusion channels, and is conducive to reversible ion insertion and extraction. Therefore, the key to improving the ion kinetics of sodium battery precursors lies in constructing a stable main structure with more ion transport channels. Summary of the invention

[0005] The technical problem to be solved by the present invention is that in the existing manganese-based layered oxide system battery, Mn 3+ There is a Jahn-Taylor distortion, and Mn 3+ / Mn 4+The transformation between them causes the problem of unstable structure in the manganese-based cathode material, resulting in a short cycle life and a sharp decline in battery capacity, which limits its large-scale promotion. The purpose of the present invention is to provide a sodium ion precursor material with a double concentration gradient and a preparation method thereof. Starting from the microstructure of the material, based on the design of a double concentration gradient composite structure of manganese-iron-nickel-copper, the synthesized precursor has excellent active crystal planes, which is conducive to the insertion and extraction of sodium ions and can improve the structural stability of the electrode material.

[0006] A sodium ion precursor material with a double concentration gradient, which has a chemical composition with the following general formula: Ni x Mn y Fe 0.9-x-y Cu z A 0.1-z (OH) 2 , where 0.2 ≤ x ≤ 0.4, 0.3 ≤ y ≤ 0.5, 0.05 ≤ z ≤ 0.1, and A is composed of one or more elements among Co, Al, Zn, Mg, Ti, and Zr; moreover, the Ni and Cu elements increase from the center to the surface, and the Mn and Fe elements decrease from the center to the surface.

[0007] The surface of the Ni and Cu elements is 120-170% of the central content, and the surface of the Mn and Fe elements is 60-80% of the central content; in the entire precursor material, the Ni / Cu molar ratio is 2-4, and the Mn / Fe molar ratio is 1-2.

[0008] The median particle size D50 of the precursor material is 2.5-12.5 μm, the particle size span is 0.5-1.1, the tapped density TD is 0.9-1.9 g / cm 3 , and the loose bulk density AD is 0.6-1.0 g / cm 3 , the specific surface area is 20-80 m 2 / g, and the surface of the precursor is loose and porous, and the primary particles are in the shape of strips or petals, with a size of 50-250 nm.

[0009] The preparation method of the above-mentioned sodium ion precursor material with a double concentration gradient includes the following steps:

[0010] Step 1, according to the stoichiometric ratio, simultaneously add the salt solutions of Ni, Fe, Mn, Cu, and M metal to the reaction system, and simultaneously add the precipitant solution and the complexing agent solution;

[0011] The addition rate of the salt solutions of Ni and Cu changes from slow to fast, and the addition rate of the salt solutions of Fe and Mn changes from fast to slow;

[0012] Step 2, after the addition of the salt solutions is completed, continue to react for a certain period of time, filter out the precipitate, wash it, and dry it to obtain the precursor.

[0013] In the said step 1, the salt solutions of Ni, Fe, and Mn refer to sulfate solutions, and the salt solutions of Cu and metal M refer to nitrate solutions.

[0014] The ratio of the initial feeding flow rates of the salt solutions of Ni, Cu, Mn, and Fe is 180:40 - 80:350 - 450:150 - 250, and the ratio of their final feeding flow rates is 300:80 - 120:200 - 300:100 - 150; the ratio of the increase in the flow rate of the salt solutions of Ni and Cu to the decrease in the flow rate of the salt solutions of Mn and Fe is 12:2 - 6:10 - 20:5 - 12.

[0015] The molar concentrations of the salt solutions of Ni, Fe, and Mn are 1.0 - 2.0 mol / L; the molar concentration of the salt solution of Cu is 1.0 - 2.0 mol / L, and the molar concentration of the salt solution of metal M is 5 - 20 g / L.

[0016] The feeding flow rate of the salt solution of metal M is constant, and the ratio of the flow rate to the initial feeding flow rate of the salt solution of Ni is 50:150 - 200.

[0017] The said complexing agent solution is an ammonia water solution, and the said precipitating agent solution is a sodium hydroxide or sodium carbonate solution.

[0018] Application of the above-mentioned precursor material in preparing a sodium-ion battery, and the said application further includes a step of calcining the precursor.

[0019] The said calcining process includes the following steps: mixing the precursor with sodium carbonate according to a mass ratio of 1.0 - 1.1, pre-calcining at 300 - 400 °C for 1 - 10 h, and then calcining at 900 - 1000 °C for 5 - 15 h.

[0020] Beneficial effects

[0021] (1) In the present invention, by designing multi-channel liquid feeding through coprecipitation reaction and adjusting the flow rate to control the system concentration, not only can the material components be perfectly transitioned from the inside to the outside, realizing atomic-level co-doping of the elements of the precursor material, but also the growth direction and size of the primary particles can be adjusted during the synthesis process, exposing more active crystal planes, and providing more ion transport channels for the sintered cathode material.

[0022] (2) The design of the manganese-iron - nickel-copper double concentration gradient sodium-ion structure has a higher content of manganese and iron in the inner layer of the material, which improves the problem of Mn ion dissolution, is beneficial to the improvement of the cycle stability and voltage platform of the material. At the same time, the outer layer has a higher content of nickel and copper. The promotion of capacity by Ni 2+ / 4+ and the charge compensation by Cu 2+ are more conducive to obtaining and maintaining high capacity.

[0023] (3) Constructing a high-entropy system through multi-element doping can combine the advantages of different metal building blocks. The doping of inactive metal ions slows down the Jahn-Teller effect, making it easier for the material to exhibit more excellent sodium-ion storage performance. Description of the Drawings

[0024] Figure 1 is the first charge-discharge curve of the sodium-ion battery after calcining the precursor material prepared in Example 1;

[0025] Figure 2 is the first charge-discharge curve of the sodium-ion battery after calcining the precursor material prepared in Comparative Example 2;

[0026] Figure 3 is the first charge-discharge curve of the sodium-ion battery after calcining the precursor material prepared in Comparative Example 3;

[0027] Figure 4 is the first charge-discharge curve of the sodium-ion battery after calcining the precursor material prepared in Comparative Example 4;

[0028] Figure 5 is the SEM image of the precursor material prepared in Example 1;

[0029] Figure 6 is the SEM image of the precursor material prepared in Comparative Example 1;

[0030] Figure 7 is the SEM image of the precursor material prepared in Comparative Example 2;

[0031] Figure 8 is the cyclic performance curve graph. Detailed Description of the Invention

[0032] The present invention provides a sodium-ion precursor material with a dual concentration gradient. After calcination treatment, the precursor material can obtain a cathode material for a sodium-ion battery, which has the characteristic that in the oxide particles of the cathode material, each element shows a specific gradient distribution from the particle center to the outer shell. More specifically, the precursor material is a particle, and its chemical formula in the composition is Ni x Mn y Fe 0.9-x-y Cu z A 0.1-z (OH) 2 , where 0.2 ≤ x ≤ 0.4, 0.3 ≤ y ≤ 0.5, 0.05 ≤ z ≤ 0.1, and A is composed of one or more elements selected from Co, Al, Zn, Mg, Ti, and Zr.

[0033] The contents of the main elements Ni, Cu, Mn, and Fe in the precursor material show a gradient distribution from the center to the surface of the particles. Among them, the Ni and Cu elements increase from the center to the surface, and the surface content is 120-170% of the center content; the Mn and Fe elements decrease from the center to the surface, and the surface content is 60-80% of the center content. The content of the doping element A remains consistent from the center to the surface, ≤5 mol%.

[0034] In the precursor material described above, the Ni / Cu molar ratio is 2-4, and the Mn / Fe molar ratio is 1-2.

[0035] The median particle size D50 of the precursor material is 2.5-12.5 μm, the particle size span is 0.5-1.1, the tapped density TD is 0.9-1.9 g / cm 3 , and the loose bulk density AD is 0.6-1.0 g / cm 3 , the specific surface area is 20-80 m 2 / g. The surface of the precursor is loose and porous, and the primary particles are in the shape of laths or petals, with a size of 50-250 nm.

[0036] The present invention proposes a method for preparing the above precursor material, specifically including:

[0037] Step 1: Prepare sulfate solutions of Ni, Fe, and Mn, and adjust the pH value of the iron salt solution to be between 1 and 6 with 98% concentrated sulfuric acid, where the molar concentrations of nickel, iron, and manganese are 1.0-2.0 mol / L;

[0038] Prepare a sodium hydroxide or sodium carbonate solution with a mass fraction of 15-35% as a precipitant;

[0039] Prepare an ammonia water solution with a molar concentration of 0.25-2.0 mol / L as a complexing agent;

[0040] Prepare an additive solution doped with Cu and element A and a buffer. Adjust the pH value of the copper solution to be between 7 and 12.5 with 32% sodium hydroxide solution, where the molar concentration of Cu is 1.0-2.0 mol / L, the mass concentration of the doping element A is 5-20 g / L, and the buffer is 1-5 g / L.

[0041] Step 2: Introduce an inert atmosphere into the reaction system and start the synthesis stirring. In order to obtain a precursor material with a core-shell structure having different gradient distributions, in this patent, by regulating the feeding rates of different metal salt solutions, the coprecipitation products obtained at different stages have different compositions. Specifically, the nickel-iron-manganese solution in Step 1 is respectively controlled at a feeding rate of 100-400 ml / min to control the nickel-iron-manganese concentration in the system, and the precipitant, complexing agent, and Cu and A metal additive solutions are continuously pumped into the reaction kettle at a flow rate of 50-100 ml / min. The reaction temperature is 30-70 °C, the process rotation speed is 500-800 rpm, and the pH is controlled between 9.0 and 12 for coprecipitation reaction; in some specific embodiments, in Step 2, the molar concentrations of the nickel-iron-manganese solution and the copper additive solution are kept consistent. During the synthesis stage, the A element additive solution has a constant flow rate of 50 ml / min. At the initial synthesis stage, the nickel and copper solution flows are respectively pumped into the reaction system at 180 and 60 ml / min, and then adjusted to the target flow rates of 300 and 100 ml / min with an increment of 12 and 4 ml / min every 4 h. The flow rates of the manganese-iron mixed solution are respectively pumped into the reaction system at 400 and 200 ml / min, and then adjusted to the target flow rates of 240 and 120 ml / min with a decrement of 16 and 8 ml / min every 4 h to control the concentration of the reaction system. After all the metal solution flow rate adjustments are completed, the reaction ends after 4 h. The pH of the coprecipitation reaction is preferably in the range of 8.5-11.5, and the reaction temperature is preferably 35-65 °C.

[0042] Step 3: Subject the coprecipitation product in Step 2 to post-treatment processes of pressure filtration, washing, and drying to obtain a nickel-iron-manganese-based hydroxide precursor with a double concentration gradient;

[0043] In some specific embodiments, in Step 1, the buffer includes one or more of sodium citrate, sodium acetate, sodium succinate, and ethylenediaminetetraacetic acid.

[0044] In some specific embodiments, in Step 3, the post-treatment process uses a 1.0-2.0 mol / L sodium carbonate or sodium hydroxide solution to wash the precursor, the drying process temperature is 50-100 °C, and the drying time is 10-15 h.

[0045] Example 1

[0046] Ni 0.3 Mn 0.4 Fe 0.2 Cu 0.08 Al 0.02 (OH) 2 The preparation method of the precursor material with a double concentration gradient is as follows:

[0047] Step 1: Prepare sulfate solutions of Ni, Fe, and Mn according to the stoichiometric ratio of the chemical formula. Adjust the pH value of the iron salt solution to between 1 and 4 with 98% concentrated sulfuric acid, where the molar concentrations of nickel, iron, and manganese in the solution are all 2.0 mol / L;

[0048] Prepare a sodium hydroxide or sodium carbonate solution with a mass fraction of 32% as the precipitant;

[0049] Prepare an ammonia water solution with a molar concentration of 0.25 mol / L as the complexing agent;

[0050] Prepare two additive solutions doped with Cu and elemental Al according to the stoichiometric ratio of the chemical formula. Use a buffer solution system during the preparation. Adjust the pH value of the copper solution to between 7 and 12.5 with 32% sodium hydroxide solution, where the molar concentration of Cu is 2.0 mol / L, and the mass concentration of the doped element is 15 g / L, and the buffer added to the two solutions is 5 g / L. 3 ) 3 The mass concentration of the doped element is 15 g / L, and the buffer added to the two solutions is 5 g / L.

[0051] Step 2: Introduce an inert atmosphere into the reaction system and start the synthesis stirring. The molar concentrations of the nickel-iron-manganese solution and the copper additive solution are 2 mol / L. During the synthesis stage, the Al additive and the ammonia water complexing agent solution are respectively pumped into the reaction system at a constant flow rate of 50 and 25 ml / min. In the initial synthesis stage, the nickel and copper solution flow rates are respectively pumped into the reaction system at 180 and 60 ml / min, and then adjusted to the target flow rates of 300 and 100 ml / min with an increment of 12 and 4 ml / min every 4 h until all are added dropwise. The manganese-iron mixed solution flow rates are respectively pumped into the reaction system at 400 and 200 ml / min, and then adjusted to the target flow rates of 240 and 120 ml / min with a decrement of 16 and 8 ml / min every 4 h to control the reaction system concentration until all are added. After all the metal solution flow rate adjustments are completed, continue for 4 h to end the reaction. The pH of the coprecipitation reaction is in the range of 9.0 - 11.5, and the reaction temperature is 40 °C.

[0052] Step 3: Subject the coprecipitation product obtained in Step 2 to post-treatment processes of pressure filtration, washing, and drying to obtain a nickel-iron-copper-manganese-aluminum precursor with a double concentration gradient.

[0053] Comparative Example 1

[0054] The difference from Example 1 is that the doping of Al is not introduced.

[0055] Ni 0.3 Mn 0.4 Fe 0.2 Cu 0.1 (OH) 2 The preparation method of the precursor material with a double concentration gradient is as follows:

[0056] Step 1: Prepare sulfate solutions of Ni, Fe, and Mn according to the stoichiometric ratio of the chemical formula. Adjust the pH value of the iron salt solution to between 1 and 4 with 98% concentrated sulfuric acid, where the molar concentrations of nickel, iron, and manganese in the solution are all 2.0 mol / L;

[0057] Prepare a sodium hydroxide or sodium carbonate solution with a mass fraction of 32% as the precipitating agent;

[0058] Prepare an ammonia water solution with a molar concentration of 0.25 mol / L as the complexing agent;

[0059] Prepare a Cu additive solution according to the stoichiometric ratio of the chemical formula. During the preparation, use a buffer solution system. Adjust the pH value of the copper solution to between 10 and 11 with 32% sodium hydroxide solution, where the molar concentration of Cu is 2.0 mol / L, and add 5 g / L of buffer agent to the solution.

[0060] Step 2: Introduce an inert atmosphere into the reaction system and start the synthesis stirring. The molar concentrations of the nickel, iron, manganese solution and the copper additive solution are 2 mol / L. During the synthesis stage, the ammonia water complexing agent solution is pumped into the reaction system at a constant flow rate of 25 ml / min. At the initial synthesis stage, the nickel and copper solution flows are pumped into the reaction system at 180 and 60 ml / min respectively. Subsequently, every 4 h, the flow rates are adjusted incrementally by 12 and 4 ml / min to the target flow rates of 300 and 100 ml / min until all are added dropwise. The manganese and iron mixed solution flows are pumped into the reaction system at 400 and 200 ml / min respectively. Subsequently, every 4 h, the flow rates are adjusted decrementally by 16 and 8 ml / min to the target flow rates of 240 and 120 ml / min to control the concentration of the reaction system until all are added. After all the metal solution flow rate adjustments are completed, continue for 4 h to end the reaction. The pH of the coprecipitation reaction is in the range of 9.5 - 10.5, and the reaction temperature is 40°C.

[0061] Step 3: Filter, wash, and dry the coprecipitation product from Step 2 through a post-treatment process to obtain a nickel, iron, copper, manganese precursor with a double concentration gradient.

[0062] Comparative Example 2

[0063] The difference from Example 1 is that the addition rate of the nickel, copper, manganese, iron solution is constant.

[0064] Ni 0.3 Mn 0.4 Fe 0.2 Cu 0.08 Al 0.02 (OH) 2 The preparation method of the precursor material is as follows:

[0065] Step 1: Prepare sulfate solutions of Ni, Fe, and Mn according to the stoichiometric ratio of the chemical formula. Adjust the pH value of the iron salt solution to between 1 and 4 with 98% concentrated sulfuric acid, where the molar concentrations of nickel, iron, and manganese in the solution are all 2.0 mol / L;

[0066] Prepare a sodium hydroxide or sodium carbonate solution with a mass fraction of 32% as a precipitant;

[0067] Prepare an ammonia water solution with a molar concentration of 0.25 mol / L as a complexing agent;

[0068] According to the stoichiometric ratio of the chemical formula, prepare two additive solutions doped with Cu and elemental Al. During the preparation, use a buffer solution system. Adjust the pH value of the copper solution to between 10 and 11 with 32% sodium hydroxide solution, where the molar concentration of Cu is 2.0 mol / L, and the mass concentration of the doped element Al is 15 g / L, and the buffer added to both solutions is 5 g / L. 3 ) 3 The mass concentration of the doped element is 15 g / L, and the buffer added to both solutions is 5 g / L.

[0069] Step 2: Introduce an inert atmosphere into the reaction system and start the synthesis stirring. The molar concentrations of the nickel-iron-manganese solution and the copper additive solution are 2 mol / L. During the synthesis stage, the Al additive, Cu additive, and ammonia water complexing agent solution are respectively pumped into the reaction system at a constant flow rate of 50, 50, and 25 ml / min, and the nickel, iron, and manganese solution flow rates are respectively 150, 100, and 200 ml / min. After all are added, continue the reaction for 4 h. The pH of the coprecipitation reaction is in the range of 9.5 - 10.5, and the reaction temperature is 40 °C.

[0070] Step 3: Subject the coprecipitation product in Step 2 to post-treatment processes of pressure filtration, washing, and drying to obtain a nickel-iron-copper-manganese-aluminum precursor with a uniform distribution.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that the addition rate of the nickel-copper-manganese-iron solution is constant.

[0073] Ni 0.3 Mn 0.4 Fe 0.2 Cu 0.08 Al 0.02 (OH) 2 The preparation method of the precursor material is as follows:

[0074] Step 1: Prepare sulfate solutions of Ni, Fe, and Mn according to the stoichiometric ratio of the chemical formula. Adjust the pH value of the iron salt solution to between 1 and 4 with 98% concentrated sulfuric acid, where the molar concentrations of nickel, iron, and manganese in the solution are all 2.0 mol / L;

[0075] Prepare a sodium hydroxide or sodium carbonate solution with a mass fraction of 32% as the precipitant;

[0076] Prepare an ammonia water solution with a molar concentration of 0.25 mol / L as the complexing agent;

[0077] According to the stoichiometric ratio of the chemical formula, prepare two additive solutions doped with Cu and elemental Al. During the preparation, a buffer solution system is used. Adjust the pH value of the copper solution to between 10 and 11 with 32% sodium hydroxide solution. The molar concentration of Cu is 2.0 mol / L, and the mass concentration of the doped element is 15 g / L. Add 5 g / L of buffer agent to both solutions. 3 ) 3 The mass concentration of the doped element is 15 g / L, and 5 g / L of buffer agent is added to both solutions.

[0078] Step 2: Introduce an inert atmosphere into the reaction system and start the synthesis stirring. The molar concentrations of the nickel-iron-manganese solution and the copper additive solution are 2 mol / L. During the synthesis stage, the Al additive and the ammonia water complexing agent solution are respectively pumped into the reaction system at a constant flow rate of 50 and 25 ml / min, and the nickel, copper, iron, and manganese solution flow rates are respectively 240, 80, 320, and 160 ml / min. After all are added, continue the reaction for 4 h. The pH of the coprecipitation reaction is in the range of 9.5 - 10.5, and the reaction temperature is 40°C.

[0079] Step 3: Filter, wash, and dry the coprecipitation product obtained in Step 2 through a post-treatment process to obtain a uniformly distributed nickel-iron-copper-manganese-aluminum precursor.

[0080] Battery testing method

[0081] After mixing the precursors obtained in the above examples and comparative examples with sodium carbonate evenly by a mass ratio of 1.03, pre-burn at 350°C for 3 h in an air atmosphere, and then sinter at 950°C for 10 h to obtain a composite-phase sodium-ion cathode material.

[0082] Assemble the sintered cathode material into a coin-type 2032 battery and perform charge-discharge tests at a rate of 0.1C within a voltage window of 2.0V - 4.0V.

[0083]

[0084] From the above test results, it can be seen that compared with Comparative Example 1, in Example 1, by introducing the doping atom Al and constructing a high-entropy system through multi-element doping, the advantages of different metal building blocks can be combined. The doping of inactive metal ions slows down the Jahn-Teller effect, and the material is more likely to exhibit more excellent sodium-ion storage performance. At the same time, compared with Comparative Examples 2 and 3, in Example 1, the flow rate adjustment sequence of the precipitation process is that the flow rate of the nickel-copper solution is slow first and then fast, and the flow rate of the manganese-iron mixed solution is fast first and then slow, realizing different elemental distribution amounts in the center and on the surface. There is a higher content of manganese and iron in the inner layer of the material, improving the problem of Mn ion dissolution, which is beneficial to the improvement of the cycle stability and voltage platform of the material. At the same time, there is a higher content of nickel and copper in the outer layer. Ni 2+ / 4+ the promotion of capacity and Cu 2+ charge compensation are more conducive to the acquisition and retention of high capacity.

Claims

1. Application of a sodium ion precursor material with a double concentration gradient in the preparation of a sodium ion battery, and the application further includes a step of calcining the precursor. It is characterized in that It has a chemical composition with the following general formula: Ni x Mn y Fe 0.9-x- y Cu z A 0.1-z (OH) 2 , where 0.2 ≤ x ≤ 0.4, 0.3 ≤ y ≤ 0.5, 0.05 ≤ z ≤ 0.1, and A is Al; moreover, the Ni and Cu elements increase from the center to the surface, while the Mn and Fe elements decrease from the center to the surface; The preparation method of the sodium ion precursor material with a double concentration gradient includes the following steps: Step 1: According to the stoichiometric ratio, add salt solutions of Ni, Fe, Mn, Cu, and M metals to the reaction system simultaneously, and add a precipitant solution and a complexing agent solution at the same time; The addition rate of the salt solutions of Ni and Cu changes from slow to fast, and the addition rate of the salt solutions of Fe and Mn changes from fast to slow; Step 2: After the addition of the salt solutions is completed, continue the reaction for a certain period of time, filter out the precipitate, wash it, and dry it to obtain the precursor; In the step 1, the salt solutions of Ni, Fe, and Mn refer to sulfate solutions, and the salt solutions of Cu and M metals are nitrate solutions; The ratio of the initial addition flow rates of the salt solutions of Ni, Cu, Mn, and Fe is 180:40 - 80:350 - 450:150 - 250, and the ratio of their final addition flow rates is 300:80 - 120:200 - 300:100 - 150; the ratio of the increase in the flow rate of the salt solutions of Ni and Cu to the decrease in the flow rate of the salt solutions of Mn and Fe is 12:2 - 6:10 - 20:5 - 12; The molar concentration of the salt solutions of Ni, Fe, and Mn is 1.0 - 2.0 mol / L; the molar concentration of the salt solution of Cu is 1.0 - 2.0 mol / L, and the molar concentration of the salt solution of M metal is 5 - 20 g / L; The addition flow rate of the salt solution of M metal is constant, and the ratio of the flow rate to the initial addition flow rate of the salt solution of Ni is 50:150 - 200; The complexing agent solution is an ammonia water solution, and the precipitant solution is a sodium hydroxide or sodium carbonate solution.

2. The application according to claim 1, It is characterized in that The surface of Ni and Cu elements has a central content of 120 - 170%, and the surface of Mn and Fe elements has a central content of 60 - 80%; in the entire precursor material, the Ni / Cu molar ratio is 2 - 4, and the Mn / Fe molar ratio is 1 - 2.

3. The application according to claim 1, It is characterized in that The median particle size D50 of the precursor material is 2.5 to 12.5 μm, the particle size distance span is 0.5 to 1.1, the tapped density TD is 0.9 to 1.9 g / cm 3 , and the loose packing AD is 0.6 to 1.0 g / cm 3 , the specific surface area is 20 to 80 m 2 / g. The surface of the precursor is loose and porous, and the primary particles are in the shape of strips or petals, with a size of 50 to 250 nm.

4. The application according to claim 1, It is characterized in that The calcination process includes the following steps: Mix the precursor and sodium carbonate according to a mass ratio of 1.0 - 1.1, pre-calcine at 300 - 400 °C for 1 - 10 h, and then calcine at 900 - 1000 °C for 5 - 15 h.

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