Low-sodium sulfur carbonate precursor and preparation method thereof

Abstract

The invention relates to the technical field of battery materials, in particular to a low-sodium sulfur carbonate precursor and a preparation method thereof.The chemical general formula of the carbonate precursor is Ni1-x-yCoxMny (OH) 2m (CO3) 1-m. The preparation method comprises the following steps that S1, Ni, Co and Mn salt solutions are prepared; preparing a sodium carbonate and sodium bicarbonate solution as a precipitator; s2, introducing a protective atmosphere into a reaction system, and adding a metal salt solution and a precipitant into the kettle for a co-precipitation reaction; s3, the nickel-cobalt-manganese carbonate subjected to the co-precipitation reaction is subjected to simple primary water washing and then is dehydrated; s4, calcining the dehydrated nickel cobalt manganese carbonate in calcining equipment; and S5, washing and drying the pre-sintered nickel-cobalt-manganese oxide. According to the invention, the problem that the content of sodium and sulfur impurities in the carbonate precursor is too high is solved, and the content of Na and S impurities in the carbonate precursor is reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery materials, and in particular to a low-sodium sulfur carbonate precursor and a preparation method thereof. Background Art

[0002] NCM material is one of the important systems of lithium battery positive electrode materials. The current international mainstream NCM precursor production process adopts hydroxide co-precipitation process, with NaOH as precipitant and ammonia water as complexing agent, which can produce spherical hydroxide precursors with high tap density.

[0003] The carbonate co-precipitation process offers certain advantages from a cost-effective perspective. Even without the use of a complexing agent, it can produce precursor particles with a high degree of sphericity. However, the main drawbacks of the carbonate process are poor process stability and difficulty controlling the nucleation particle size. The higher Na / S content of carbonate precursor impurities compared to hydroxide precursors affects the electrochemical performance of the sintered cathode material, limiting the widespread adoption of carbonate precursor synthesis.

[0004] In response to the problem of high Na / S content, the carbonate process, as the main supplementary route for the mainstream hydroxide co-precipitation process, needs to be solved urgently. Many domestic hydroxide precursor technology routes use alkaline washing (sodium hydroxide, sodium carbonate or sodium bicarbonate solution) to utilize ion replacement of sulfate, but this introduces Na impurity content and increases the amount of washing water. In addition, unlike the layered structure of the hydroxide series precursors, the carbonate precursor has a dense structure, and it is difficult to completely remove Na impurity ions from the inside or surface of the particles during washing. However, there are few studies on methods to reduce the Na / S impurity content of carbonate precursors.

[0005] Therefore, how to solve the shortcomings of the existing technical problems has become the subject to be studied and solved by the present invention. Summary of the Invention

[0006] In view of this, the present invention provides a low-sodium thiocarbonate precursor and a preparation method thereof.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: a low sodium sulfur carbonate precursor, the carbonate precursor chemical formula is: Ni 1-x-y Co x Mn y (OH) 2m (CO3) 1-m , wherein 0≤x<1, 0≤y≤0.75, x+y≥0.2, 0<m<0.2, the anions of the precursor material include hydroxide and carbonate, the carbonate content is distributed in a gradient decreasing manner from the inside to the outside, the carbonate / hydroxyl molar ratio is greater than 1.5, the median particle size D50 of the nickel-cobalt-manganese carbonate precursor is 3-12 μm, and the Span value is 0.4-1.2.

[0008] As a further description of the above technical solution:

[0009] The structure of the low sodium thiocarbonate precursor is a structure that is dense on the outside and loose on the inside.

[0010] A method for preparing a low-sodium thiocarbonate precursor comprises the following steps:

[0011] S1, prepare nickel, cobalt and manganese mixed salt solution, prepare sodium bicarbonate solution as precipitant 1, prepare sodium carbonate solution as precipitant 2, prepare reaction base liquid, the base liquid pH is 4-6;

[0012] S2, adding a bottom liquid into the reactor and introducing an inert gas, starting synthesis stirring, the first synthesis stage: first, the nickel-cobalt-manganese mixed salt solution and the precipitant 1 in step S1 are pumped into the reactor simultaneously, the reaction temperature is controlled at 30-70°C, the pH is 6-8, the synthetic average particle size D50 is 2-7 μm, and the span value is 0.4-0.8; the second synthesis stage: suspending the feeding of the precipitant 1 and the nickel-cobalt-manganese mixed salt solution and instead pumping the precipitant 2 into the reaction system, controlling the reaction temperature at 50-70°C, adjusting the pH to 8-9.5, and pumping the nickel-cobalt-manganese mixed salt solution again, controlling the solid content to 25-45%, and the pH to 8.5-10. When the average particle size D50 of the reaction system slurry is 3-12 μm and the span value is 0.4-1.2, stopping the feeding of the nickel-cobalt-manganese mixed salt solution and the precipitant 2 to obtain a nickel-cobalt-manganese carbonate precursor slurry;

[0013] S3, preliminarily washing and dehydrating the nickel-cobalt-manganese carbonate precursor to obtain nickel-cobalt-manganese carbonate with a Na content of less than 500 ppm and a S content of less than 1000 ppm;

[0014] S4, calcining the dehydrated nickel-cobalt-manganese carbonate in a calcination device at a calcination temperature of 150-600° C. for 4-15 hours;

[0015] S5. Wash and dry the nickel-cobalt-manganese oxide calcined in step S4 to obtain a low-sodium thiocarbonate precursor with a Na content of ≤200 ppm and a S content of ≤500 ppm.

[0016] As a further description of the above technical solution:

[0017] In step S1, the molar concentration of the nickel-cobalt-manganese mixed salt solution is 1.0-2.25 mol / L, the molar concentration of sodium bicarbonate is 0.5-1.0 mol / L, and the molar concentration of sodium carbonate is 1.5-2.5 mol / L. The base liquid is an acidic solution of sodium carbonate and sulfuric acid, or a mixed solution of a nickel-cobalt-manganese metal salt solution and sulfuric acid.

[0018] As a further description of the above technical solution:

[0019] In the first stage synthesis stage of step S2, the inlet flow ratio of sodium bicarbonate to the nickel-cobalt-manganese mixed solution is greater than 2.0, the molar ratio of sodium bicarbonate to the nickel-cobalt-manganese mixed solution is greater than 1.0, the concentration of the nickel-cobalt-manganese mixed salt is preferably 2.0-2.25 mol / L, and the concentration of sodium bicarbonate is preferably 1.0 mol / L.

[0020] As a further description of the above technical solution:

[0021] In the second synthesis stage of step S2, the inlet flow ratio of sodium carbonate to the nickel-cobalt-manganese mixed solution is greater than 1.0, the molar ratio of sodium carbonate to the nickel-cobalt-manganese mixed solution is greater than 2.0, and the sodium carbonate concentration is 1.5-2.5 mol / L.

[0022] As a further description of the above technical solution:

[0023] The preliminary washing in step S3 is to use ammonium carbonate solution as a washing liquid to wash the nickel-cobalt-manganese carbonate precursor after the mother liquor is removed from the nickel-cobalt-manganese carbonate precursor. The mass concentration of the ammonium carbonate solution is 5%-50%, the solution temperature is 5-50°C, and the water content of the dehydrated nickel-cobalt-manganese carbonate precursor is controlled at 5%-25%.

[0024] As a further description of the above technical solution:

[0025] The calcination temperature curve in step S4 is divided into two stages. The first stage is heating from 25°C to 150°C and holding the temperature for 2-5 hours; the second stage is heating from 150°C to 300-600°C and holding the temperature for 2-10 hours.

[0026] As a further description of the above technical solution:

[0027] In step S5, the mass ratio of the nickel-cobalt-manganese carbonate precursor to the washing hot pure water is between 1:1 and 1:5, the temperature of the hot pure water is between 40-80°C, the drying temperature is between 100-180°C, and the moisture content of the dried precursor is controlled at 0.1%-0.5%.

[0028] By means of the above technical solution, the present invention has at least the following beneficial effects:

[0029] 1. Compared with the existing technology, the surface of the carbonate precursor has a stronger negative charge CO3 2- , which easily adsorbs Na in the reaction system + , resulting in higher impurity ions, a low sodium thiocarbonate precursor and its preparation method are synthesized in a staged manner. The first stage uses sodium bicarbonate as a precipitant HCO3 - Reduce the surface charge, Na + The impurity adsorption capacity is low, thereby reducing the sodium impurity content in the precursor.

[0030] 2. Compared with the prior art, the low sodium thiocarbonate precursor and its preparation method adjust the concentration of the sodium carbonate precipitant in the reaction system and control the synthesis pH range of 8-10. The basic carbonate generated in the second stage of synthesis changes from the original dense structure of carbonate to a layered structure, which is beneficial to the subsequent washing process to reduce the Na / S impurity content;

[0031] 3. Compared with the prior art, the low-sodium sulfur carbonate precursor and its preparation method use ammonium carbonate solution as the primary washing liquid. Under alkaline conditions, the ion exchange capacity of carbonate ions is greater than that of sulfate impurity ions, and sulfate is replaced and removed without introducing sodium impurity ion content. The material after the initial washing is calcined at 300-500°C, and the nickel-cobalt-manganese carbonate precursor is decomposed into nickel-cobalt-manganese oxide. The ammonium carbonate remaining after washing is decomposed and removed, and the sodium carbonate decomposition temperature is relatively high (above 800°C) and the residual sodium carbonate on the surface of the nickel-cobalt-manganese oxide is dissolved and removed by hot water washing to achieve the effect of reducing the Na content. After sintering, the oxide is directly mixed with lithium and sintered, which increases the loading capacity of the positive electrode sintering sagger, shortens the positive electrode sintering process, and improves production efficiency.

[0032] 4. Compared with the prior art, this low sodium sulfur carbonate precursor and its preparation method form a composite structure of basic nickel cobalt manganese carbonate Ni by controlling the precipitant and concentration in different synthesis stages. 1-x-y Co x Mn y (OH) 2m (CO3) 1-m The carbonate anion content gradually decreases from the inside to the outside, and the hydroxide content gradually increases. The moisture content of the dehydrated material is 15%. The carbonate sintering temperature is lower than that of the hydroxide system. The gradient distribution structure of the basic carbonate precursor material is conducive to the uniform sintering of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the SEM image of Example 1 proposed by the present invention;

[0034] Figure 2 This is the SEM image of Example 2 proposed by the present invention;

[0035] Figure 3 This is the SEM image of Example 3 proposed by the present invention;

[0036] Figure 4 This is the XRD pattern of Example 1 proposed in the present invention. DETAILED DESCRIPTION

[0037] Reference Figure 1-4 The present invention provides a low sodium sulfur carbonate precursor: the carbonate precursor chemical formula is: Ni1-x-y Co x Mn y (OH) 2m (CO3) 1-m , wherein 0≤x<1, 0≤y≤0.75, x+y≥0.2, 0<m<0.2, the anions of the precursor material include hydroxide and carbonate, the carbonate content is distributed in a gradient decreasing manner from the inside to the outside, the carbonate / hydroxyl molar ratio is greater than 1.5, the median particle size D50 of the nickel cobalt manganese carbonate precursor is 3-12 μm, and the Span value is 0.4-1.2.

[0038] The structure of the low-sodium sulfur carbonate precursor is dense on the outside and loose on the inside. The temperature required inside the precursor during sintering is lower than that on the outside. The dense outer and loose inner structure is not easy to overburn, and the loose structure is also conducive to the washing of Na ion impurities. At the same time, the dense outer and loose inner structure has better wettability with the positive electrode material and the electrolyte after sintering, providing a volume expansion effect buffer during the charge and discharge process, exposing more reaction active sites, accelerating the migration of ions, and facilitating capacity maintenance.

[0039] The positively charged main layer of carbonate and its interlayer anions form a layered structure, forming a structural transformation, expanding the lithium ion transmission channel, and the sintered positive electrode is conducive to the release of rate performance. In addition, in order to balance the anion charge, it is easier to form a divalent metal state and a trivalent metal mixed state, which is similar to the effect of doping.

[0040] The present invention provides a method for preparing a low-sodium thiocarbonate precursor, comprising the following steps:

[0041] S1. Prepare a nickel-cobalt-manganese mixed salt solution, specifically, the molar concentration of the nickel-cobalt-manganese mixed salt solution is 1.0-2.25 mol / L, prepare a sodium bicarbonate solution as a first precipitant, specifically, the molar concentration of sodium bicarbonate is 0.5-1.0 mol / L, prepare a sodium carbonate solution as a second precipitant, specifically, the molar concentration of sodium carbonate is 1.5-2.5 mol / L, prepare a reaction base solution, specifically, the base solution is an acidic solution of sodium carbonate and sulfuric acid, or a mixed solution of nickel-cobalt-manganese metal salt solution and sulfuric acid, and the pH of the base solution is 4-6;

[0042] S2, add bottom liquid into the reactor and pass inert gas, start synthesis stirring, the first synthesis stage: first, the nickel-cobalt-manganese mixed salt solution and the precipitant in step S1 are pumped into the reactor together, the reaction temperature is controlled to be 30-70°C, the pH is 6-8, preferably 6.5-7.5, the synthetic average particle size D50 is 2-7 μm, and the span value is 0.4-0.8. Specifically, in the first stage synthesis stage, the inlet flow ratio of sodium bicarbonate to the nickel-cobalt-manganese mixed solution is greater than 2.0, the molar ratio of sodium bicarbonate to the nickel-cobalt-manganese mixed solution is greater than 1.0, the concentration of the nickel-cobalt-manganese mixed salt is 1.0-2.25 mol / L, and the concentration of sodium bicarbonate is preferably 1.0 mol / L; the second synthesis stage: suspend the precipitant. and changing the nickel-cobalt-manganese mixed salt solution into the reaction system by pumping the precipitant second, controlling the reaction temperature to 50-70° C., adjusting the pH to 8-10, pumping the nickel-cobalt-manganese mixed salt solution again, controlling the solid content to 25-45%, the pH to 8.5-10, preferably the pH to 9.0-9.5, and stopping the nickel-cobalt-manganese mixed salt solution and the precipitant second when the average particle size D50 of the reaction system slurry is 3-12 μm and the span value is 0.4-1.2 to obtain a nickel-cobalt-manganese carbonate precursor slurry. Specifically, in the second synthesis stage, the inlet flow ratio of sodium carbonate to the nickel-cobalt-manganese mixed solution is greater than 1.0, the molar ratio of sodium carbonate to the nickel-cobalt-manganese mixed solution is greater than 2.0, and the sodium carbonate concentration is 2.0-2.5 mol / L;

[0043] S3. Preliminary washing and dehydration of the nickel-cobalt-manganese carbonate precursor to obtain a nickel-cobalt-manganese carbonate with a Na content of <500 ppm and a S content of <1000 ppm. Specifically, the preliminary washing is performed by using an ammonium carbonate solution as a washing liquid to wash the nickel-cobalt-manganese carbonate precursor after removing the mother liquor from the nickel-cobalt-manganese carbonate precursor. The mass concentration of the ammonium carbonate solution is 5%-50%, and the solution temperature is 5-50° C., preferably the mass concentration of the ammonium carbonate solution is 15-30%, and the solution temperature is 15-35° C. The water content of the dehydrated nickel-cobalt-manganese carbonate precursor is controlled to be 5%-25%, preferably 15%-25%;

[0044] S4. calcining the dehydrated nickel-cobalt-manganese carbonate in a calcination device at a calcination temperature of 150-600° C. for 4-15 hours. Specifically, the calcination temperature curve is divided into two stages: the first stage is heating from 25° C. to 150° C. and holding the temperature for 2-5 hours; the second stage is heating from 150° C. to 300-600° C. and holding the temperature for 2-10 hours.

[0045] S5. Wash and dry the nickel-cobalt-manganese oxide calcined in step S4 to obtain a low-sodium sulfur carbonate precursor having a Na content of ≤200 ppm and a S content of ≤500 ppm. Specifically, the mass ratio of the nickel-cobalt-manganese carbonate precursor to washing hot pure water is between 1:1 and 1:5, the temperature of the hot pure water is between 40-80° C., the drying temperature is between 100-180° C., and the moisture content of the dried precursor is controlled to be between 0.1% and 0.5%.

[0046] The environment for preparing the low-sodium sulfur carbonate precursor is weakly alkaline, and the reaction bottom liquid is acidic. The synthesized precursor structure has a small core and is more loose inside under acidic conditions. The sintering of this precursor is easier to reduce energy consumption.

[0047] Example 1:

[0048] Ni 0.6 Co 0.2 Mn 0.2 (OH) 0.36 (CO3) 0.82 The preparation method of the precursor material is as follows:

[0049] Step 1: prepare a mixed salt solution with a molar ratio of Ni, Co, and Mn of 6:2:2, wherein the molar concentration of nickel, cobalt, and manganese is 2.0 mol / L;

[0050] Sodium carbonate and sodium bicarbonate solutions were prepared as precipitants, with the molar concentration of sodium carbonate being 2.0 mol / L and the molar concentration of sodium bicarbonate being 1.0 mol / L;

[0051] Prepare the reaction base solution by adding a mixed solution of nickel, cobalt, manganese metal salt solution and sulfuric acid, with a pH range of 4.5;

[0052] Step 2: Inert gas is introduced into the reactor system, and synthesis stirring is started. In the first synthesis stage, the nickel-cobalt-manganese mixed solution of step 1 is first pumped into the reaction system at a flow rate of 2000 ml / h and a sodium bicarbonate solution of 4500 ml / h in parallel, and the reaction temperature is controlled at 50°C, the pH is 6-7, and the sodium bicarbonate and nickel-cobalt-manganese mixed salt are suspended when the average particle size D50 of the slurry is 5 μm; in the second synthesis stage, the precipitant is changed to sodium carbonate and pumped into the reaction system at a flow rate of 4500 ml / h, the pH is adjusted to 9, and the nickel-cobalt-manganese mixed metal salt is pumped again at a flow rate of 2000 ml / h, the solid content is controlled at 25-45%, the reaction temperature is 50°C, and the synthesis pH range is 9.5-10.0. When the average particle size D50 of the reaction system slurry is 8 μm, the nickel-cobalt-manganese mixed salt and sodium carbonate are stopped to obtain a nickel-cobalt-manganese carbonate precursor slurry.

[0053] Step 3: First, nickel cobalt manganese carbonate precursor Ni 0.6 Co 0.2 Mn 0.2 (OH) 0.36 (CO3) 0.82 The mother liquor was removed by centrifugation, and then the filter cake was initially washed and dehydrated using a 20% ammonium carbonate solution at 40°C at a washing volume of 5 L / kg of the precursor. The moisture content of the filter cake was about 15%.

[0054] Step 4: The dehydrated carbonate precursor in step 1 is placed in a calcining furnace for pre-sintering. The first stage is heated from room temperature to 150°C and kept at this temperature for 2 hours. The second stage is heated from 150°C to 400°C and kept at this temperature for 10 hours.

[0055] Step 5: Finally, the pre-sintered material in step 2 is washed with hot water, washed twice with 60°C hot water at 2.5 L / kg of the sintered material, and the washed material is dried at 150°C to obtain nickel-cobalt-manganese oxide with low sodium and sulfur content.

[0056] Example 2:

[0057] Ni 0.6 Co 0.2 Mn 0.2 (OH) 0.24 (CO3) 0.88 The preparation method of the precursor material is as follows:

[0058] Step 1: prepare a mixed salt solution with a molar ratio of Ni, Co, and Mn of 6:2:2, wherein the molar concentration of nickel, cobalt, and manganese is 2.0 mol / L;

[0059] Sodium carbonate and sodium bicarbonate solutions were prepared as precipitants, with the molar concentration of sodium carbonate being 2.0 mol / L and the molar concentration of sodium bicarbonate being 1.0 mol / L;

[0060] Prepare the reaction base solution, add sodium carbonate solution and dilute sulfuric acid to adjust the base solution to acidity, pH range 4.5;

[0061] Step 2: Inert gas is introduced into the reactor system, and synthesis stirring is started. In the first synthesis stage, the nickel-cobalt-manganese mixed solution of step 1 is first pumped into the reaction system at a flow rate of 2000 ml / h and a sodium bicarbonate solution of 4000 ml / h in parallel, and the reaction temperature is controlled at 50°C, the pH is 6-7, and the sodium bicarbonate and nickel-cobalt-manganese mixed salt feeds are suspended when the average particle size D50 of the slurry is 5 μm; in the second synthesis stage, the precipitant is changed to sodium carbonate and pumped into the reaction system at a flow rate of 2500 ml / h, the pH is adjusted to 9, and the nickel-cobalt-manganese mixed metal salt is pumped again at a flow rate of 2000 ml / h, the solid content is controlled at 25-45%, the reaction temperature is 50°C, and the synthesis pH range is 9.0-9.5. When the average particle size D50 of the reaction system slurry is 8 μm, the nickel-cobalt-manganese mixed salt and sodium carbonate feeds are stopped to obtain a nickel-cobalt-manganese carbonate precursor slurry.

[0062] Step 3: First, nickel cobalt manganese carbonate precursor Ni 0.6 Co 0.2 Mn 0.2 (OH) 0.24 (CO3) 0.88The mother liquor was removed by centrifugation, and then the filter cake was initially washed and dehydrated using a 20% ammonium carbonate solution at 40°C at a washing volume of 5 L / kg of the precursor. The moisture content of the filter cake was about 15%.

[0063] Step 4: The dehydrated carbonate precursor in step 1 is placed in a calcining furnace for pre-sintering. The first stage is heated from room temperature to 150°C and kept at this temperature for 2 hours. The second stage is heated from 150°C to 400°C and kept at this temperature for 10 hours.

[0064] Step 5: Finally, the pre-sintered material in step 2 is washed with hot water, washed twice with 60°C hot water at 2.5 L / kg of the sintered material, and the washed material is dried at 150°C to obtain nickel-cobalt-manganese oxide with low sodium and sulfur content.

[0065] Example 3:

[0066] Ni 0.6 Co 0.2 Mn 0.2 (OH) 0.12 (CO3) 0.94 The preparation method of the precursor material is as follows:

[0067] Step 1: prepare a mixed salt solution with a molar ratio of Ni, Co, and Mn of 6:2:2, wherein the molar concentration of nickel, cobalt, and manganese is 2.0 mol / L;

[0068] Sodium carbonate and sodium bicarbonate solutions were prepared as precipitants, with the molar concentration of sodium carbonate being 2.0 mol / L and the molar concentration of sodium bicarbonate being 1.0 mol / L;

[0069] Prepare the reaction base solution, add sodium carbonate solution and dilute sulfuric acid to adjust the base solution to acidity, pH range 4.5;

[0070] Step 2: Inert gas is introduced into the reactor system, and synthesis stirring is started. In the first synthesis stage, the nickel-cobalt-manganese mixed solution of step 1 is first pumped into the reaction system at a flow rate of 2000 ml / h and a sodium bicarbonate solution of 4000 ml / h in parallel, and the reaction temperature is controlled at 50°C, the pH is 6-7, and the sodium bicarbonate and nickel-cobalt-manganese mixed salt are suspended when the average particle size D50 of the slurry is 5 μm; in the second synthesis stage, the precipitant is changed to sodium carbonate and pumped into the reaction system at a flow rate of 2500 ml / h, the pH is adjusted to 9, and the nickel-cobalt-manganese mixed metal salt is pumped again at a flow rate of 2000 ml / h, the solid content is controlled at 25-45%, the reaction temperature is 50°C, and the synthesis pH range is 8.5-9.0. When the average particle size D50 of the reaction system slurry is 8 μm, the nickel-cobalt-manganese mixed salt and sodium carbonate are stopped to obtain a nickel-cobalt-manganese basic carbonate precursor slurry.

[0071] Step 3: First, nickel cobalt manganese carbonate precursor Ni 0.6 Co 0.2 Mn0.2 (OH) 0.12 (CO3) 0.94 The mother liquor was removed by centrifugation, and then the filter cake was initially washed and dehydrated using a 20% ammonium carbonate solution at 40°C at a washing volume of 5 L / kg of the precursor. The moisture content of the filter cake was about 15%.

[0072] Step 4: The dehydrated carbonate precursor in step 1 is placed in a calcining furnace for pre-sintering. The first stage is heated from room temperature to 150°C and kept at this temperature for 2 hours. The second stage is heated from 150°C to 400°C and kept at this temperature for 10 hours.

[0073] Step 5: Finally, the pre-sintered material in step 2 is washed with hot water, washed twice with 60°C hot water at 2.5 L / kg of the sintered material, and the washed material is dried at 150°C to obtain nickel-cobalt-manganese oxide with low sodium and sulfur content.

[0074] Comparative Example 1:

[0075] Ni 0.6 Co 0.2 Mn 0.2 The preparation method of the CO3 precursor material is as follows:

[0076] Step 1: prepare a mixed salt solution with a molar ratio of Ni, Co, and Mn of 6:2:2, wherein the molar concentration of nickel, cobalt, and manganese is 2.0 mol / L;

[0077] Prepare a sodium carbonate solution as a precipitant, the molar concentration of sodium carbonate is 2.0 mol / L;

[0078] Prepare the reaction base solution, add sodium carbonate solution and dilute sulfuric acid to adjust the base solution to acidity, pH range 4.5;

[0079] Step 2: Inert gas is introduced into the reactor system, synthesis stirring is started, and the nickel-cobalt-manganese mixed solution of step 1 is first pumped into the reaction system at a flow rate of 2000 ml / h and the sodium carbonate solution at a flow rate of 3000 ml / h. The reaction temperature is controlled at 50°C, the pH is 7.5-8.5, and the solid content is controlled at 25-45%. When the average particle size D50 of the reaction system slurry is 8 μm, the nickel-cobalt-manganese mixed salt and sodium carbonate are stopped from being added to obtain a nickel-cobalt-manganese carbonate precursor slurry.

[0080] Step 3: First, nickel cobalt manganese carbonate precursor Ni 0.6 Co 0.2 Mn 0.2 The mother liquor was removed by CO3 centrifugation, and then the filter cake was initially washed and dehydrated using a 40% ammonium carbonate solution at 40°C at a washing volume of 5 L / kg of the precursor. The moisture content of the filter cake was about 15%;

[0081] Step 4: The dehydrated carbonate precursor in step 1 is placed in a calcining furnace for pre-sintering. The first stage is heated from room temperature to 150°C and kept at this temperature for 2 hours. The second stage is heated from 150°C to 500°C and kept at this temperature for 10 hours.

[0082] Step 5: Finally, the pre-sintered material in step 2 is washed with hot water at 60°C at a rate of 2.5 L / kg of the sintered material. After washing, the material is dried at 150°C to obtain nickel-cobalt-manganese oxide with low sodium and sulfur content.

[0083] Comparative Example 2:

[0084] Ni 0.6 Co 0.2 Mn 0.2 The preparation method of the CO3 precursor material is as follows:

[0085] Step 1: prepare a mixed salt solution with a molar ratio of Ni, Co, and Mn of 6:2:2, wherein the molar concentration of nickel, cobalt, and manganese is 2.0 mol / L;

[0086] Prepare a sodium carbonate solution as a precipitant, the molar concentration of sodium carbonate is 2.0 mol / L;

[0087] Prepare the reaction base solution, add sodium carbonate solution and dilute sulfuric acid to adjust the base solution to acidity, pH range 4.5;

[0088] Step 2: Inert gas is introduced into the reactor system, synthesis stirring is started, and the nickel-cobalt-manganese mixed solution of step 1 is first pumped into the reaction system at a flow rate of 2000 ml / h and the sodium carbonate solution at a flow rate of 3000 ml / h. The reaction temperature is controlled at 50°C, the pH is 7.5-8.5, and the solid content is controlled at 25-45%. When the average particle size D50 of the reaction system slurry is 8 μm, the nickel-cobalt-manganese mixed salt and sodium carbonate are stopped from being added to obtain a nickel-cobalt-manganese carbonate precursor slurry.

[0089] Step 3: First, nickel cobalt manganese carbonate precursor Ni 0.6 Co 0.2 Mn 0.2 The mother liquor was removed by CO3 centrifugation, and then 4% sodium hydroxide solution was used for the initial washing and dehydration at a washing volume of 5 L / kg of the precursor. The moisture content of the filter cake was about 15%;

[0090] Step 4: Wash the dehydrated carbonate precursor material in step 1 with hot water, washing twice with hot water at 60°C at a rate of 2.5 L / kg of carbonate precursor material;

[0091] Step 5: Finally, the washed material in step 2 is dried at 150° C. to obtain a nickel-cobalt-manganese carbonate precursor.

[0092] Comparative Example 3:

[0093] Ni0.6 Co 0.2 Mn 0.2 The preparation method of the CO3 precursor material is as follows:

[0094] Step 1: prepare a mixed salt solution with a molar ratio of Ni, Co, and Mn of 6:2:2, wherein the molar concentration of nickel, cobalt, and manganese is 2.0 mol / L;

[0095] Prepare a sodium carbonate solution as a precipitant, the molar concentration of sodium carbonate is 2.0 mol / L;

[0096] Prepare the reaction base solution, add sodium carbonate solution and dilute sulfuric acid to adjust the base solution to acidity, pH range 4.5;

[0097] Step 2: Inert gas is introduced into the reactor system, synthesis stirring is started, and the nickel-cobalt-manganese mixed solution of step 1 is first pumped into the reaction system at a flow rate of 2000 ml / h and the sodium carbonate solution at a flow rate of 3000 ml / h. The reaction temperature is controlled at 50°C, the pH is 7.5-8.5, and the solid content is controlled at 25-45%. When the average particle size D50 of the reaction system slurry is 8 μm, the nickel-cobalt-manganese mixed salt and sodium carbonate are stopped from being added to obtain a nickel-cobalt-manganese carbonate precursor slurry.

[0098] Step 3: First, nickel cobalt manganese carbonate precursor Ni 0.6 Co 0.2 Mn 0.2 The mother liquor was removed by CO3 centrifugation, and then 4% sodium hydroxide solution was used for the initial washing and dehydration at a washing volume of 5 L / kg of the precursor. The moisture content of the filter cake was about 15%;

[0099] Step 4: The alkali-washed and dehydrated carbonate precursor in step 1 is placed in a calcining furnace for pre-sintering. The first stage is heated from room temperature to 150°C and kept warm for 2 hours. The second stage is heated from 150°C to 500°C and kept warm for 10 hours.

[0100] Step 5: Finally, the pre-sintered material in step 2 is washed with hot water at 60°C at a rate of 2.5 L / kg of the sintered material. After washing, the material is dried at 150°C to obtain nickel-cobalt-manganese oxide with low sodium and sulfur content.

[0101] Table 1 is a comparison of Na / S contents in different embodiments.

[0102] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Na / ppm 143 152 198 509 2509 1828 S / ppm 382 449 496 1112 5155 4437

[0103] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low sodium thiocarbonate precursor, characterized in that: The general chemical formula of the carbonate precursor is: Ni 1-x-y Co x Mn y (OH) 2m (CO3) 1-m , wherein 0≤x<1, 0≤y≤0.75, x+y≥0.2, 0<m<0.2, the anions of the precursor material include hydroxide and carbonate, the carbonate content is distributed in a gradient decreasing manner from the inside to the outside, the carbonate / hydroxyl molar ratio is greater than 1.5, the median particle size D50 of the nickel-cobalt-manganese carbonate precursor is 3-12 μm, and the Span value is 0.4-1.

2.

2. A low sodium thiocarbonate precursor according to claim 1, characterized in that: The structure of the low sodium thiocarbonate precursor is a structure that is dense on the outside and loose on the inside.

3. The method for preparing a low sodium thiocarbonate precursor is characterized in that: The following steps are involved: S1, prepare nickel, cobalt and manganese mixed salt solution, prepare sodium bicarbonate solution as precipitant 1, prepare sodium carbonate solution as precipitant 2, prepare reaction base liquid, the base liquid pH is 4-6; S2, adding a bottom liquid into the reactor and introducing an inert gas, starting synthesis stirring, the first synthesis stage: first, the nickel-cobalt-manganese mixed salt solution and the precipitant 1 in step S1 are pumped into the reactor simultaneously, the reaction temperature is controlled at 30-70°C, the pH is 6-8, the synthetic average particle size D50 is 2-7 μm, and the span value is 0.4-0.8; the second synthesis stage: suspending the feeding of the precipitant 1 and the nickel-cobalt-manganese mixed salt solution and instead pumping the precipitant 2 into the reaction system, controlling the reaction temperature at 50-70°C, adjusting the pH to 8-9.5, and pumping the nickel-cobalt-manganese mixed salt solution again, controlling the solid content to 25-45%, and the pH to 8.5-10. When the average particle size D50 of the reaction system slurry is 3-12 μm and the span value is 0.4-1.2, stopping the feeding of the nickel-cobalt-manganese mixed salt solution and the precipitant 2 to obtain a nickel-cobalt-manganese carbonate precursor slurry; S3, preliminarily washing and dehydrating the nickel-cobalt-manganese carbonate precursor to obtain nickel-cobalt-manganese carbonate with a Na content of less than 500 ppm and a S content of less than 1000 ppm; S4, calcining the dehydrated nickel-cobalt-manganese carbonate in a calcination device at a calcination temperature of 150-600° C. for 4-15 hours; S5. Wash and dry the nickel-cobalt-manganese oxide calcined in step S4 to obtain a low-sodium thiocarbonate precursor with a Na content of ≤200 ppm and a S content of ≤500 ppm.

4. The method for preparing a low sodium thiocarbonate precursor according to claim 3, wherein: In step S1, the molar concentration of the nickel-cobalt-manganese mixed salt solution is 1.0-2.25 mol / L, the molar concentration of sodium bicarbonate is 0.5-1.0 mol / L, and the molar concentration of sodium carbonate is 1.5-2.5 mol / L. The base liquid is an acidic solution of sodium carbonate and sulfuric acid.

5. The method for preparing a low sodium thiocarbonate precursor according to claim 3, wherein: In the first stage synthesis stage of step S2, the inlet flow ratio of sodium bicarbonate to the nickel-cobalt-manganese mixed solution is greater than 2.0, the molar ratio of sodium bicarbonate to the nickel-cobalt-manganese mixed solution is greater than 1.0, the concentration of the nickel-cobalt-manganese mixed salt is preferably 2.0-2.25 mol / L, and the concentration of sodium bicarbonate is preferably 1.0 mol / L.

6. The method for preparing a low sodium thiocarbonate precursor according to claim 3, wherein: In the second synthesis stage of step S2, the inlet flow ratio of sodium carbonate to the nickel-cobalt-manganese mixed solution is greater than 1.0, the molar ratio of sodium carbonate to the nickel-cobalt-manganese mixed solution is greater than 2.0, and the concentration of sodium carbonate is 1.5-2.5 mol / L.

7. The method for preparing a low sodium thiocarbonate precursor according to claim 3, wherein: The preliminary washing in step S3 is to use ammonium carbonate solution as a washing liquid to wash the nickel-cobalt-manganese carbonate precursor after the mother liquor is removed from the nickel-cobalt-manganese carbonate precursor. The mass concentration of the ammonium carbonate solution is 5%-50%, the solution temperature is 5-50°C, and the water content of the dehydrated nickel-cobalt-manganese carbonate precursor is controlled at 5%-25%.

8. The method for preparing a low sodium thiocarbonate precursor according to claim 3, wherein: The calcination temperature curve in step S4 is divided into two stages. The first stage is heating from 25°C to 150°C and holding the temperature for 2-5 hours; the second stage is heating from 150°C to 300-600°C and holding the temperature for 2-10 hours.

9. The method for preparing a low sodium thiocarbonate precursor according to claim 3, wherein: In step S5, the mass ratio of the nickel-cobalt-manganese carbonate precursor to the washing hot pure water is between 1:1 and 1:5, the temperature of the hot pure water is between 40-80°C, the drying temperature is between 100-180°C, and the moisture content of the dried precursor is controlled at 0.1%-0.5%.

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