Method for removing sodium and sulfur from high-nickel ternary precursor and high-nickel ternary precursor

Abstract

The invention provides a method for removing sodium and sulfur from a high-nickel ternary precursor and the high-nickel ternary precursor. The method for removing sodium and sulfur from the high-nickel ternary precursor comprises the following steps: obtaining a high-nickel ternary precursor crude product; placing the high-nickel ternary precursor crude product in an organic lithium swelling solution for swelling ultrasonic treatment, and then standing and separating for the first time to obtain a high-nickel ternary precursor base solution A; carrying out primary hot alkali soaking operation on the high-nickel ternary precursor base solution A, wherein a solution used in the primary hot alkali soaking operation is a mixed solution of a sodium-containing alkaline solution and an amino carboxylic acid complexing solution; and sequentially carrying out secondary standing separation, secondary hot alkali soaking operation, ultrasonic vibration treatment, suction filtration, primary hot water washing and drying to obtain the high-nickel ternary precursor. According to the method, the good sodium and sulfur removal effect on the interior of the high-nickel ternary precursor is achieved, the effect of repairing the microcracks of the high-nickel ternary precursor is achieved, the high BET index is met, and the structural stability of the high-nickel ternary precursor is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of positive electrode materials for lithium-ion batteries, and in particular to a method for removing sodium and sulfur from a high-nickel ternary precursor and a high-nickel ternary precursor. Background Art

[0002] Precursor is one of the important raw materials for producing positive electrode materials for lithium-ion batteries. 80% of the performance indicators of the precursor will be directly transferred to the positive electrode material, and the impurity content will directly affect the electrochemical performance of the positive electrode material. At present, the industry's precursors are mainly synthesized by coprecipitation, and nickel sulfate, cobalt sulfate, manganese sulfate, liquid alkali, and ammonia water are flowed into the reactor in parallel to prepare a ternary precursor. + and SO4 2- It will enter the ternary precursor with the coprecipitation reaction. If more impurity ions enter the positive electrode material with the ternary precursor, it will seriously affect the capacity and cycle life of the positive electrode material. 2- In the subsequent sintering process of the ternary positive electrode material, corresponding pollutant gases will be generated, causing corrosion to the calcination equipment.

[0003] Therefore, the removal of Na and S in ternary precursors is particularly important. In the early days, the ternary precursor industry mainly removed Na by water washing, and there were two main measures to remove S: 1. Adjust the pH in the reaction process to strictly control the crystallization conditions to remove it, but the pH control stability is high and it is easy to affect the BET index; 2. After removing the mother liquor in the washing process, remove sodium by water washing and sulfur by alkali washing, but usually only remove Na and S impurities adsorbed on the surface of the precursor, and it is difficult to remove Na and S impurities hidden inside the crystal.

[0004] In order to better remove the Na and S impurities in the precursor, Chinese patent document No. CN112234187A discloses a method for washing and removing the impurity sodium from a nickel-cobalt-manganese ternary precursor, wherein the crude ternary precursor product after the first step of washing is put into a formamide aqueous solution and stirred thoroughly, so as to utilize the molecular polarity and intermolecular force of formamide water to open the lamellae of the crude ternary precursor product, increase the distance between the lamellae of the crude ternary precursor product, weaken the interlayer force, and reduce the SO4 existing in the ternary precursor interlayer after simple washing. 2- 、Na + Although the added formamide molecules can effectively remove the sodium-sulfur content, the formamide molecules will cause cracks on the surface of the ternary precursor in the process of increasing the interlayer spacing. The cracks will cause the BET index of the ternary precursor to be too large, resulting in low structural stability of the ternary precursor, which will lead to safety problems such as structural collapse or short circuit during the use of lithium-ion batteries. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a method for removing sodium and sulfur from a high-nickel ternary precursor and a high-nickel ternary precursor, which can achieve the effect of removing sodium and sulfur from the inside of the high-nickel ternary precursor and repairing microcracks in the high-nickel ternary precursor.

[0006] The purpose of this disclosure is achieved through the following technical solutions:

[0007] A method for removing sodium and sulfur from a high-nickel ternary precursor comprises the following steps:

[0008] Obtaining a high-nickel ternary precursor crude product;

[0009] The high-nickel ternary precursor crude product is placed in an organic lithium swelling solution for swelling ultrasonic treatment to obtain a high-nickel ternary precursor slurry A;

[0010] The high-nickel ternary precursor slurry A is subjected to a first static separation to obtain a high-nickel ternary precursor bottom liquid A;

[0011] The high-nickel ternary precursor base liquid A is subjected to a hot alkali soaking operation to obtain a high-nickel ternary precursor slurry B, wherein the solution during the hot alkali soaking operation is a mixture of a sodium-containing alkaline solution and an aminocarboxylic acid complexing solution;

[0012] The high-nickel ternary precursor slurry B is subjected to a second static separation to obtain a high-nickel ternary precursor bottom liquid B;

[0013] The high-nickel ternary precursor bottom solution B is subjected to a secondary hot alkali soaking operation to obtain a high-nickel ternary precursor slurry C, wherein the solution during the secondary hot alkali soaking operation is an alkaline solution containing lithium;

[0014] Performing ultrasonic vibration treatment on the high-nickel ternary precursor slurry C;

[0015] The high-nickel ternary precursor slurry C treated with ultrasonic vibration is filtered to obtain a high-nickel ternary precursor filter residue;

[0016] Performing a first hot water wash on the high-nickel ternary precursor filter residue;

[0017] The high-nickel ternary precursor filter residue after the first hot water washing is dried to obtain a high-nickel ternary precursor.

[0018] In one embodiment, the preparation of the mixture of the sodium-containing alkaline solution and the aminocarboxylic acid complex solution comprises the following steps:

[0019] Obtaining the sodium-containing alkaline solution with a mass percentage concentration of 2.5% to 30%;

[0020] The aminocarboxylic acid complex liquid with a concentration of 2.5 g / L to 3.5 g / L is added to the sodium-containing alkaline solution to obtain a mixed solution of the sodium-containing alkaline solution and the aminocarboxylic acid complex liquid.

[0021] In one embodiment, the sodium-containing alkaline solution comprises at least one of a sodium hydroxide solution, a sodium carbonate solution and a sodium bicarbonate solution; and / or,

[0022] The aminocarboxylic acid complexing liquid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and hydroxyethylethylenediaminetriacetic acid.

[0023] In one of the embodiments, the mass percentage concentration of the lithium-containing alkaline solution is 2.5% to 15%.

[0024] In one embodiment, the high-nickel ternary precursor is NCM811, and the average particle size of the high-nickel ternary precursor is greater than 10 μm.

[0025] In one of the embodiments, the mass percentage concentration of the organic lithium swelling solution is 5% to 30%.

[0026] In one embodiment, the solute of the organic lithium swelling solution includes at least one of n-butyl lithium, isobutyl lithium, tert-butyl lithium, sec-butyl lithium and methyl lithium; and / or,

[0027] The solvent of the organic lithium swelling solution includes at least one of ethyl ether, diethylene glycol dimethyl ether, hexane and petroleum ether.

[0028] In one embodiment, the ultrasonic frequency of the swelling ultrasonic treatment is 40KHz to 60KHz, the time of the swelling ultrasonic treatment is 0.5h to 1h; the temperature of the swelling ultrasonic treatment is 20°C to 30°C; and / or,

[0029] The temperature of the hot alkali soaking operation is 60°C to 70°C, and the time of the hot alkali soaking operation is 1h to 2h; and / or,

[0030] The temperature of the secondary hot alkali soaking operation is 60°C to 70°C, and the time of the secondary hot alkali soaking operation is 1h to 2h; and / or,

[0031] The ultrasonic frequency of the ultrasonic vibration treatment is 40KHz to 60KHz, and the time of the ultrasonic vibration treatment is 5min to 10min; and / or,

[0032] The temperature of the first hot water washing is 60°C to 70°C.

[0033] In one embodiment, before the step of obtaining the high-nickel ternary precursor crude product, the method further includes the following steps:

[0034] The mother liquor is subjected to a removal operation to obtain a solid high-nickel ternary precursor crude product;

[0035] washing the solid high-nickel ternary precursor crude product with hot water for a second time;

[0036] The solid high-nickel ternary precursor crude product that has been washed with hot water for the second time is filtered to obtain the high-nickel ternary precursor crude product.

[0037] A high-nickel ternary precursor is prepared by the method for removing sodium and sulfur from a high-nickel ternary precursor described in any of the above embodiments.

[0038] Compared with the prior art, the present invention has at least the following advantages:

[0039] 1) Since the added organic lithium swelling solution can undergo ion exchange reaction with the high nickel ternary precursor crude product, the Li + It can capture the H of the crude product of high nickel ternary precursor + , generating alkane macromolecules to insert into the interlayer, increasing the interlayer spacing of the high nickel ternary precursor and weakening the electrostatic attraction between the layers of the high nickel ternary precursor; making the Li released from the organic lithium swelling solution + Can replace H in the crude product of high nickel ternary precursor + 's location, and because of Li + The hydration energy of Li is large, making + The hydration repulsion formed between the layers is greater than the weakened electrostatic attraction between the layers, so that the layers of the high-nickel ternary precursor will be pushed outward, and this thrust helps to increase the distance between the layers, and with the help of weak ultrasonic oscillation of swelling ultrasonic treatment, Li + It is easier to enter the interlayer of the high-nickel ternary precursor to achieve good swelling of the interlayer of the high-nickel ternary precursor, so that the sheets of the crude product of the high-nickel ternary precursor are loose and the specific surface area is increased, that is, the initial swelling of the interlayer of the high-nickel ternary precursor is achieved, which is beneficial to the expansion of water and OH - It is easier to enter the interlaminar space and convert the Na inside the crystal of the high nickel ternary precursor into + 、SO4 2- By replacing them, the initial removal of Na and S from the high-nickel ternary precursor can be achieved.

[0040] 2) Since the high nickel ternary precursor base liquid A is soaked in hot alkali once with a mixture of a sodium-containing alkaline solution and an aminocarboxylic acid complex solution, the OH in the mixture of the sodium-containing alkaline solution and the aminocarboxylic acid complex solution is - It can fully enter the layers and convert the SO4 inside the crystal of the high nickel ternary precursor 2-The sodium-containing alkaline solution can dissolve the surface and microcrack surface of the high-nickel ternary precursor in trace amounts, so as to form nickel-cobalt-manganese metal ions in the high-nickel ternary precursor slurry B, thereby providing sufficient metal ions for the subsequent repair of microcracks; the carboxyl and amino groups with strong coordination ability in the added aminocarboxylic acid complexing solution can form complexes with free nickel-cobalt-manganese metal ions, and the generated complexes will react with OH in the first hot alkali soaking and the second hot alkali soaking operation. - A co-precipitation reaction occurs, so that the microcracks of the high-nickel ternary precursor are fully repaired and improved, thereby achieving the effect of repairing the microcracks of the high-nickel ternary precursor, ensuring that the BET index of the high-nickel ternary precursor is qualified, thereby ensuring the structural stability of the high-nickel ternary precursor, and thereby ensuring that safety problems such as structural collapse or short circuit are not prone to occur during the use of lithium-ion batteries.

[0041] 3) Due to Li + The ionic radius is smaller than that of Na + , so that the interlayer of the high nickel ternary precursor is Li + Affinity than Na + Stronger, when the high nickel ternary precursor is operated in a secondary hot alkaline soaking operation, the Li in the lithium-containing alkaline solution + It can well enter the interlayer of high nickel ternary precursor to replace Na + , further reducing the impurity Na content, and Li + As the raw material of positive electrode material, it does not pose an impurity threat and plays a role of pre-lithiation; and, since the organic lithium swelling solution has achieved the initial swelling of the interlayer of the high nickel ternary precursor, it is beneficial to the Li of the lithium-containing alkaline solution. + The ions are well inserted into the interlayer of the high-nickel ternary precursor to form an intercalation compound. At the same time, under the action of weak ultrasonic vibration treatment, the interlayer of the high-nickel ternary precursor is enlarged and swollen again, that is, the secondary enlargement and swelling of the interlayer of the high-nickel ternary precursor is achieved, which is beneficial to the separation of water and OH. - Better access to the interlayer to transfer Na + and SO4 2- Replace them to further reduce the impurity Na and S content of the high-nickel ternary precursor.

[0042] 4) Due to the coordinated effect of the swelling ultrasonic treatment of the organic lithium swelling solution and the secondary hot alkali immersion operation of the lithium-containing alkaline solution, the high-nickel ternary precursor achieves double swelling, the interlayer spacing of the high-nickel ternary precursor increases, and the internal volume of the particles increases, which is manifested as an increase in specific surface area. The specific surface area increases with the extension of the alkali immersion time. Therefore, it can be used as an effective means to control the specific surface area index in the production process of the high-nickel ternary precursor, that is, by adjusting the length of the secondary alkali immersion time, the specific surface area of ​​the high-nickel ternary precursor can be controlled to better meet the production requirements of the BET indicators of different high-nickel ternary precursors.

[0043] 5) The high nickel ternary precursor residue is washed with hot water for the first time to effectively remove the impurities Na on the surface of the high nickel ternary precursor. + 、SO4 2- , which is conducive to the preparation of a high-nickel ternary precursor with low Na and S content, qualified BET indicators and stable structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 This is a flow chart of a method for removing sodium and sulfur from a high-nickel ternary precursor according to one embodiment of the present invention;

[0046] Figure 2 The SEM images of the high nickel ternary precursor of Comparative Example 1 of the present invention at 5w times and 1k times (the left image is 5w times, and the right image is 1k times);

[0047] Figure 3 The SEM images of the high nickel ternary precursor of Example 1 of the present invention at 5w times and 1k times (the left image is 5w times, and the right image is 1k times);

[0048] Figure 4 The SEM images of the high nickel ternary precursor of Example 3 of the present invention at 5w times and 1k times (the left image is 5w times, and the right image is 1k times);

[0049] Figure 5 These are 5w times and 1k times SEM pictures of the high nickel ternary precursor of Example 5 of the present invention (the left picture is 5w times, and the right picture is 1k times). DETAILED DESCRIPTION

[0050] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0051] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0053] The present invention provides a method for removing sodium and sulfur from a high-nickel ternary precursor, comprising the following steps: obtaining a high-nickel ternary precursor crude product; placing the high-nickel ternary precursor crude product in an organic lithium swelling solution for swelling ultrasonic treatment to obtain a high-nickel ternary precursor slurry A; performing a first static separation on the high-nickel ternary precursor slurry A to obtain a high-nickel ternary precursor bottom liquid A; performing a hot alkali soaking operation on the high-nickel ternary precursor bottom liquid A to obtain a high-nickel ternary precursor slurry B, wherein the solution during the hot alkali soaking operation is a mixture of a sodium-containing alkaline solution and an aminocarboxylic acid complexing solution; The nickel ternary precursor slurry B is subjected to a second static separation to obtain a high-nickel ternary precursor bottom liquid B; the high-nickel ternary precursor bottom liquid B is subjected to a second hot alkali soaking operation to obtain a high-nickel ternary precursor slurry C, wherein the solution during the second hot alkali soaking operation is an alkaline solution containing lithium; the high-nickel ternary precursor slurry C is subjected to ultrasonic vibration treatment; the high-nickel ternary precursor slurry C subjected to ultrasonic vibration treatment is filtered to obtain a high-nickel ternary precursor filter residue; the high-nickel ternary precursor filter residue is subjected to a first hot water wash; the high-nickel ternary precursor filter residue subjected to the first hot water wash is dried to obtain a high-nickel ternary precursor.

[0054] The above-mentioned method for removing sodium and sulfur from the high-nickel ternary precursor, through the coordinated use of swelling ultrasonic treatment, one hot alkali soaking operation, two hot alkali soaking operations and ultrasonic vibration treatment, enables the organic lithium swelling solution to achieve the initial swelling of the high-nickel ternary precursor, and achieves the effect of preliminary removal of Na and S from the high-nickel ternary precursor; it is conducive to the sodium-containing alkaline solution in the subsequent one hot alkali soaking operation to replace the SO4 inside the crystal of the high-nickel ternary precursor 2- , and is also beneficial to the subsequent secondary hot alkali soaking operation in the lithium-containing alkaline solution + Enter the interlayer of the high-nickel ternary precursor to replace Na + , in conjunction with the effect of ultrasonic vibration treatment, the secondary enlargement and swelling of the interlayer of the high-nickel ternary precursor is achieved, and the impurity Na and S content of the high-nickel ternary precursor is further reduced; and the sodium-containing alkaline solution can dissolve the surface and microcrack surface of the high-nickel ternary precursor in trace amounts, so as to form nickel, cobalt and manganese metal ions in the high-nickel ternary precursor slurry B, thereby providing sufficient metal ions for the subsequent repair of microcracks, so that the carboxyl and amino groups with strong coordination ability in the added aminocarboxylic acid complexing solution can form complexes with free nickel, cobalt and manganese metal ions, and the generated complexes will react with OH in the first hot alkali soaking and the second hot alkali soaking operation. - A co-precipitation reaction occurs, so that the microcracks of the high-nickel ternary precursor are fully repaired and improved, thereby achieving the effect of repairing the microcracks of the high-nickel ternary precursor, ensuring that the BET index of the high-nickel ternary precursor is qualified, thereby ensuring the structural stability of the high-nickel ternary precursor, and thereby ensuring that safety problems such as structural collapse or short circuit are not prone to occur during the use of lithium-ion batteries.

[0055] In order to better understand the technical solutions and beneficial effects of the present invention, the present invention is further described in detail below in conjunction with specific embodiments:

[0056] See also Figure 1 The method for removing sodium and sulfur from a high-nickel ternary precursor in one embodiment includes some or all of the following steps:

[0057] S101, obtaining a crude product of a high-nickel ternary precursor for later use.

[0058] In one embodiment, the high-nickel ternary precursor is NCM811, and the average particle size of the high-nickel ternary precursor is greater than 10 μm.

[0059] It can be understood that the current high-nickel ternary precursor NCM811 has a Na content of 300ppm and a S content of about 2200ppm, which leads to the problem of high Na and S content in NCM811. Therefore, NCM811 needs to be de-sodiumed and de-sulfurized.

[0060] It can be understood that when the average particle size of the high nickel ternary precursor is greater than 10 μm, the high nickel ternary precursor with an average particle size greater than 10 μm is more likely to induce microcracks in the high nickel ternary precursor due to the presence of more stress in the crystal during the generation of the high nickel ternary precursor crystal. In this way, on the one hand, the structural stability of the high nickel ternary precursor is affected, and on the other hand, the high nickel ternary precursor is prone to cracking or breaking under the action of external force. The traditional method of removing sodium and sulfur causes the microcracks to be more obvious in the process of increasing the interlayer spacing, so as to cause the structural stability of the high nickel ternary precursor to be worse. Therefore, it is necessary to repair the microcracks of the high nickel ternary precursor with a particle size greater than 10 μm to ensure that the preparation of the high nickel ternary precursor with a high BET index, a stable structure, and a low content of Na and S is obtained.

[0061] In one of the embodiments, the particle size of the high nickel ternary precursor is 10 μm to 11 μm.

[0062] In one embodiment, before the step of obtaining the high-nickel ternary precursor crude product, the following steps are also included: first, the mother liquor is stripped to remove most of the Na + 、SO4 2- , to obtain Na + 、SO4 2- Then, the solid high-nickel ternary precursor crude product is washed with hot water for a second time to remove a small amount of Na adsorbed on the surface of the solid high-nickel ternary precursor crude product particles. + 、SO4 2- ; Finally, the solid high-nickel ternary precursor crude product that has been washed with hot water for the second time is filtered to obtain the high-nickel ternary precursor crude product.

[0063] It can be understood that during the first hot water washing and the second hot water washing, the impurity Na + 、SO4 2- The principle is divided into two steps: ① The impurity ions overcome the adsorption effect of the crystal surface of the high-nickel ternary precursor and migrate out from the crystal interface of the high-nickel ternary precursor, and form a saturated layer at the interface between the impurity ions and water; ② Under the action of diffusion, the impurity ions diffuse from the saturated layer to the unsaturated layer, and then diffuse into the water to dissolve, so as to achieve the removal effect of the impurity ions.

[0064] It can also be understood that the adsorption of impurities on the crystal surface of the high-nickel ternary precursor is an exothermic reaction. The lower the temperature, the easier it is for the impurity ions to be adsorbed and the harder it is for the impurity ions to migrate out. The higher the temperature, the greater the thermal motion rate of the ions and the faster the diffusion rate. Therefore, the higher the water temperature, the faster the rate at which impurities migrate into the water and the easier it is to remove the impurities. Therefore, the temperatures of the first and second hot water washes are both 60°C to 70°C to effectively remove the impurities Na on the surface of the high-nickel ternary precursor. + 、SO4 2- , thereby preparing a high-purity high-nickel ternary precursor.

[0065] In one of the embodiments, the step of removing the mother liquor includes the following specific steps: first, taking the raw slurry prepared in the reactor, and then placing the raw slurry in a suction filtration bottle for filtration to effectively remove the mother liquor and separate the solid high-nickel ternary precursor crude product.

[0066] In one embodiment, the second hot water washing operation includes the following specific steps: adding 60°C to 70°C hot pure water to the suction filtration bottle for washing, and the washing time is 1min to 5min to remove Na adsorbed on the surface of the solid high-nickel ternary precursor crude product particles. + 、SO4 2- .

[0067] In one embodiment, the step of filtering the solid high-nickel ternary precursor crude product after the second hot water wash includes the following specific steps: filtering the dry solid high-nickel ternary precursor crude product, and separating the filtered high-nickel ternary precursor crude product from the filter paper to obtain the high-nickel ternary precursor crude product for standby use.

[0068] S102, placing the crude high-nickel ternary precursor product in an organic lithium swelling solution for swelling ultrasonic treatment to obtain a high-nickel ternary precursor slurry A.

[0069] It can be understood that since the chemical formula of the high nickel ternary precursor is Ni x Co y Mn 1-x-y (OH)2, and has a layered structure. The upper and lower surfaces of the single-layer structure are OH, and the two O atoms are connected to Ni, Co, and Mn ions. The added organic lithium swelling solution can disconnect the OH in the high-nickel ternary precursor to capture H + Alkanes are generated, that is, the added organic lithium swelling solution and the high nickel ternary precursor crude product can undergo ion exchange reaction, so that the Li + It can capture the H of the crude product of high nickel ternary precursor +, generating alkane macromolecules to insert into the interlayer, increasing the interlayer spacing of the high nickel ternary precursor and weakening the electrostatic attraction between the layers of the high nickel ternary precursor; making the Li released from the organic lithium swelling solution + It can replace the position of H+ in the crude product of high nickel ternary precursor, and because Li + The hydration energy of Li is large, making + The hydration repulsion formed between the layers is greater than the weakened electrostatic attraction between the layers, so that the layers of the high-nickel ternary precursor will be pushed outward, and this thrust helps to increase the distance between the layers, and with the help of weak ultrasonic oscillation of swelling ultrasonic treatment, Li + It is easier to enter the interlayer of the high-nickel ternary precursor to achieve good swelling of the interlayer of the high-nickel ternary precursor, so that the sheets of the crude product of the high-nickel ternary precursor are loose and the specific surface area is increased, that is, the initial swelling of the interlayer of the high-nickel ternary precursor is achieved, which is beneficial to the expansion of water and OH - It is easier to enter the interlaminar space and convert the Na inside the crystal of the high nickel ternary precursor into + 、SO4 2- By replacing them, the initial removal of Na and S from the high-nickel ternary precursor can be achieved.

[0070] It can be understood that if the mass percentage concentration of the organic lithium swelling solution is less than 5%, the lithium concentration content in the organic lithium swelling solution is too low and the swelling between the layers of the high-nickel ternary precursor cannot be increased; if the mass percentage concentration of the organic lithium swelling solution is greater than 30%, the lithium ion concentration of the organic lithium swelling solution will be too high, resulting in a large amount of lithium ions being excessively inserted into the inter-layer structure of the high-nickel ternary precursor, causing more microcracks and affecting the structural stability of the high-nickel ternary precursor. Therefore, in one of the embodiments, the mass percentage concentration of the organic lithium swelling solution is 5% to 30% to ensure that the lithium concentration content in the added organic lithium swelling solution is appropriate. In this way, under the premise of satisfying the swelling to increase the interlayer spacing of the high-nickel ternary precursor, it is also ensured that the added organic lithium swelling solution will not cause the high-nickel ternary precursor to produce too many microcracks, thereby ensuring that the high-nickel ternary precursor finally prepared can both meet the BET index and maintain structural stability, effectively avoiding the problem of the organic lithium swelling solution causing more microcracks due to excessive concentration and affecting the structural stability of the high-nickel ternary precursor.

[0071] In one embodiment, the solute of the organic lithium swelling solution includes at least one of n-butyl lithium, isobutyl lithium, tert-butyl lithium, sec-butyl lithium and methyl lithium, and in particular, the solvent of the organic lithium swelling solution includes at least one of ether, diethylene glycol dimethyl ether, hexane and petroleum ether, so as to ensure that the added organic lithium swelling solution can achieve good swelling and enlargement of the interlayer of the high nickel ternary precursor.

[0072] It can be understood that since the solvents of the organic lithium swelling solution, such as ether, diethylene glycol dimethyl ether, hexane and petroleum ether, have certain volatility, when the organic lithium swelling solution and the crude product of the high-nickel ternary precursor are subjected to swelling ultrasonic treatment, the solute and solvent of the organic lithium swelling solution can enter the interlayer of the high-nickel ternary precursor well with the micro-vibration of the swelling ultrasonic treatment, so that the organic lithium swelling solution can achieve good swelling and increase of the interlayer of the high-nickel ternary precursor, and effectively reduce the problem of more microcracks in the high-nickel ternary precursor caused by too fast or too high swelling between the layers of the high-nickel ternary precursor.

[0073] It can be understood that if the ultrasonic frequency of the swelling ultrasonic treatment is less than 40KHz or the time of the swelling ultrasonic treatment is less than 0.5h, the smaller ultrasonic frequency or the shorter time of the swelling ultrasonic treatment cannot achieve sufficient and comprehensive vibration of the high nickel ternary precursor crude product, thereby failing to achieve a good swelling and enlargement effect on the high nickel ternary precursor crude product; if the ultrasonic frequency of the swelling ultrasonic treatment is greater than 60KHz or the time of the swelling ultrasonic treatment is greater than 1h, the larger ultrasonic frequency or the longer time of the swelling ultrasonic treatment will cause the swelling and enlarged high nickel ternary precursor to be prone to more microcracks or falling off. Therefore, in one embodiment, the ultrasonic frequency of the swelling ultrasonic treatment is 40KHz to 60KHz, and the time of the swelling ultrasonic treatment is 0.5h to 1h; to ensure that the use of weak ultrasonic oscillations of the swelling ultrasonic treatment can achieve sufficient, comprehensive and stable swelling and enlargement of the high nickel ternary precursor layer, so as to ensure that the prepared high nickel ternary precursor has less Na and S content, qualified BET index and stable structure.

[0074] It should be noted that, since ether, diethylene glycol dimethyl ether, hexane and petroleum ether have certain volatility, if the temperature of the swelling ultrasonic treatment is a heating treatment, the organic lithium swelling solution enters the interlayer of the high nickel ternary precursor too fast, causing the interlayer swelling of the high nickel ternary precursor to increase too fast, resulting in the high nickel ternary precursor to produce more microcracks to affect the structural stability of the high nickel ternary precursor. Therefore, in one embodiment, the temperature of the swelling ultrasonic treatment is 20°C to 30°C, especially the ultrasonic frequency of the swelling ultrasonic treatment is 40KHz to 60KHz, and the swelling ultrasonic treatment time is 0.5h to 1h, so as to ensure that the ternary precursor can achieve stable and reliable swelling and increase under the action of the organic lithium swelling solution, so that the sheet of the crude product of the high nickel ternary precursor is loose, the specific surface area is increased, and it is conducive to the prepared high nickel ternary precursor. The content of Na and S is less, the BET index is qualified and the structure is stable.

[0075] S103, the high nickel ternary precursor slurry A is subjected to a first static separation, so that the Na + 、SO42- It can be dissolved in the high-nickel ternary precursor slurry. When the high-nickel ternary precursor slurry is subjected to the first static separation, the high-nickel ternary precursor will sink to the bottom to form a layer, and the upper part is a clear liquid. Then pour out the upper clear liquid to remove Na + 、SO4 2- , and obtain a high-nickel ternary precursor bottom liquid A with low Na and S content.

[0076] S104, performing a hot alkali soaking operation on the high-nickel ternary precursor base liquid A to obtain a high-nickel ternary precursor slurry B, wherein the solution during the hot alkali soaking operation is a mixture of a sodium-containing alkaline solution and an aminocarboxylic acid complexing solution.

[0077] It can be understood that after the crystallization of the high nickel ternary precursor is completed, the interlamellar force will 2- Firmly adsorbed, and the OH in the mother liquor - The reaction has basically been completed, OH - It is difficult to enter the crystal interlamellar of the high nickel ternary precursor to convert SO4 2- Therefore, the high nickel ternary precursor needs to be swollen first to weaken the interlayer force and increase the internal volume of the crystal of the high nickel ternary precursor, which is beneficial to OH - Enter the crystal to replace SO4 2- , so that the OH in the mixture of sodium alkaline solution and aminocarboxylic acid complex solution - It can fully enter the layers of the high-nickel ternary precursor and convert the SO4 2- It is replaced to effectively remove the S impurities inside the crystal of the high-nickel ternary precursor, thereby reducing the impurity S content.

[0078] It should be noted that although the interlayer spacing of the high-nickel ternary precursor can be stably and reliably increased by placing the crude high-nickel ternary precursor in an organic lithium swelling solution for swelling ultrasonic treatment, the high-nickel ternary precursor still has the problem of microcracks. Therefore, in the present disclosure, since the sodium-containing alkaline solution can dissolve the surface and microcrack surface of the high-nickel ternary precursor in trace amounts, so as to form nickel-cobalt-manganese metal ions in the high-nickel ternary precursor slurry B, and thus provide sufficient metal ions for the subsequent repair of microcracks, the carboxyl and amino groups with strong coordination ability in the added aminocarboxylic acid complexing solution can form complexes with the free nickel-cobalt-manganese metal ions, and the generated complexes will co-precipitate with OH- in the primary hot alkali immersion and secondary hot alkali immersion operations, so that the microcracks of the high-nickel ternary precursor are fully repaired and improved, thereby achieving the effect of repairing the microcracks of the high-nickel ternary precursor, ensuring that the BET index of the high-nickel ternary precursor is qualified, thereby ensuring the structural stability of the high-nickel ternary precursor, and thereby ensuring that safety problems such as structural collapse or short circuit are not prone to occur during the use of lithium-ion batteries.

[0079] It can also be understood that the principle of the primary hot alkali soaking operation and the secondary hot alkali soaking operation in the present disclosure is as follows: the alkali washing process can be divided into the following two steps: ① OH - Through ion exchange adsorption into the adsorption layer of the interface phase on the crystal surface of the high nickel ternary precursor, the SO4 2- ② OH in the adsorption layer - Diffusion into the crystal of high nickel ternary precursor completes the crystal transformation, and at the same time SO4 2- Replaced to the adsorption layer on the crystal surface of the high nickel ternary precursor.

[0080] It is understandable that if the alkaline solution containing sodium is too little, the added OH - The concentration is too low to fully and completely replace SO4 2- If the alkaline solution contains too much sodium, the added Na + Too high a concentration causes the introduction of Na + Too much will increase the difficulty of subsequent removal of Na impurities; if too few carboxyl groups and amino groups are added, it will not be possible to achieve a good repair of the microcracks of the high-nickel ternary precursor. If too many carboxyl groups and amino groups are added, it will not only cause material waste, but also too many carboxyl groups and amino groups will cause uneven deposition on the surface of the high-nickel ternary precursor and fail to repair the microcracks of the high-nickel ternary precursor. Therefore, in one embodiment, the preparation of the mixed solution of the sodium-containing alkaline solution and the aminocarboxylic acid complex solution includes the following steps: obtaining the sodium-containing alkaline solution with a mass percentage concentration of 2.5% to 30%; adding the aminocarboxylic acid complex solution with a concentration of 2.5g / L to 3.5g / L to the sodium-containing alkaline solution to ensure that the OH in the mixed solution of the sodium-containing alkaline solution and the aminocarboxylic acid complex solution is - The concentration, carboxyl concentration, and amino concentration are appropriate. In this way, the SO4 2- Under the premise of this, it is also possible to achieve good repair of the microcracks in the high-nickel ternary precursor and reduce the difficulty of subsequent removal of Na impurities.

[0081] In one of the embodiments, the sodium-containing alkaline solution includes at least one of a sodium hydroxide solution, a sodium carbonate solution and a sodium bicarbonate solution.

[0082] In one embodiment, the sodium-containing alkaline solution is a sodium hydroxide solution. Since the alkalinity of the sodium hydroxide solution is relatively strong, on the one hand, the high concentration of OH -The NaOH solution will increase the hydrocarbon carbon anion characteristics of the organic lithium swelling solution, that is, accelerate the ion exchange reaction rate between the organic lithium swelling solution (such as n-butyl lithium) and the high nickel ternary precursor (extract H + ), on the basis of achieving interlayer swelling, the hot alkali immersion time is extended to further fully swell the sheet layer of the high nickel ternary precursor, so that OH - Fully enter the interlayer to convert the SO4 inside the crystal of the high nickel ternary precursor 2- Replace it and reduce the impurity S content; on the other hand, high concentration of OH - The NaOH solution can dissolve the surface and microcrack surface of the high-nickel ternary precursor in trace amounts to form free nickel-cobalt-manganese metal ions, providing sufficient metal ions for the subsequent repair of microcracks to ensure that the carboxyl and amino groups in the added aminocarboxylic acid complexing solution can form complexes with the free nickel-cobalt-manganese metal ions, and then the formed complexes will react with OH - Nickel cobalt manganese hydroxide precipitation occurs to achieve good repair of the microcracks in the high-nickel ternary precursor.

[0083] It should be noted that due to the addition of sodium-containing alkaline solution, such as NaOH solution, the pH of high-nickel ternary precursor slurry B will become 10-12, breaking the dissolution-precipitation equilibrium of the high-nickel ternary precursor, causing the dissolution-precipitation equilibrium to proceed in the reverse direction, so that the sodium-containing alkaline solution can dissolve a small amount of free nickel, cobalt and manganese metal ions. The dissolved free nickel, cobalt and manganese metal ions will form complexes with carboxyl and amino groups, and then the complexes will react with OH. - Nickel cobalt manganese hydroxide precipitate is generated to repair the microcracks of the high nickel ternary precursor.

[0084] In one embodiment, the aminocarboxylic acid complexing liquid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and hydroxyethylethylenediaminetriacetic acid.

[0085] In one of the embodiments, the aminocarboxylic acid complexing liquid is ethylenediaminetetraacetic acid. It can be understood that since ethylenediaminetetraacetic acid has two N atoms and four hydroxyl O atoms on the carboxyl group, both can provide lone pairs of electrons and can enter the empty orbit of the central atom, so that the metal ions and ethylenediaminetetraacetic acid form a stable complex, which helps to form a stable nickel cobalt manganese hydroxide precipitate on the surface of the high-nickel ternary precursor, so as to achieve good repair of the microcracks of the high-nickel ternary precursor.

[0086] It is understood that if the temperature of a hot alkali soaking operation is lower than 60°C or the time of a hot alkali soaking operation is too short, the OH - It is not possible to enter the interlayer of the high-nickel ternary precursor and fully and completely replace SO4 2-If the temperature of a hot alkali soaking operation is higher than 70℃ or the time of a hot alkali soaking operation is too long, OH - The surface of the high-nickel ternary precursor will be dissolved too much, thus affecting the structural stability of the final high-nickel ternary precursor. Therefore, in one embodiment, the temperature of the hot alkali soaking operation is controlled to be 60°C to 70°C, and the time of the hot alkali soaking operation is 1h to 2h; in particular, the sodium-containing alkaline solution and the aminocarboxylic acid complexing solution are used to ensure that the addition of OH - It can fully and completely replace the SO4 inside the crystal of the high-nickel ternary precursor 2- , while ensuring that the added carboxyl and amino groups can achieve good repair of the microcracks in the high-nickel ternary precursor.

[0087] In one embodiment, the hot alkali soaking operation time is 1h to 2h to ensure that the OH - , carboxyl and amino groups can react reliably and stably with the high nickel ternary precursor, effectively avoiding the - The problem of too fast replacement speed causing more microcracks or easy falling off of the high-nickel ternary precursor can be solved. It also ensures that the carboxyl and amino groups can be evenly deposited on the surface of the high-nickel ternary precursor, which is conducive to better repairing the microcracks of the high-nickel ternary precursor.

[0088] S105, the high nickel ternary precursor slurry B is subjected to a second static separation, so that the SO4 replaced in the high nickel ternary precursor 2- It can be dissolved in high-nickel ternary precursor slurry B. When the high-nickel ternary precursor slurry B is subjected to a second static separation, the high-nickel ternary precursor will sink to the bottom to form a layer, and the upper part is a clear liquid. Then pour out the upper clear liquid to remove SO4 2- , and obtain a high-nickel ternary precursor bottom liquid B with low Na and S content.

[0089] S106, performing a secondary hot alkali soaking operation on the high-nickel ternary precursor base liquid B to obtain a high-nickel ternary precursor slurry C, wherein the solution during the secondary hot alkali soaking operation is an alkaline solution containing lithium.

[0090] It can be understood that the addition of a certain concentration of sodium-containing alkaline solution during the first hot alkali soaking process increases the Na impurity content between the high-nickel ternary precursor layers. + The ionic radius is smaller than that of Na + , so that the interlayer of the high nickel ternary precursor is Li + Affinity than Na + Stronger, when the high nickel ternary precursor is operated in a secondary hot alkaline soaking operation, the Li in the lithium-containing alkaline solution + It can well enter the interlayer of high nickel ternary precursor to replace Na+ , further reducing the impurity Na content, and Li + As the raw material of positive electrode material, it does not pose an impurity threat and plays a role of pre-lithiation; and, since the organic lithium swelling solution has achieved the initial swelling of the interlayer of the high nickel ternary precursor, it is beneficial to the Li of the lithium-containing alkaline solution. + The ions are well inserted into the interlayer of the high-nickel ternary precursor to form an intercalation compound. At the same time, under the action of weak ultrasonic vibration treatment, the interlayer of the high-nickel ternary precursor is enlarged and swollen again, that is, the secondary enlargement and swelling of the interlayer of the high-nickel ternary precursor is achieved, which is beneficial to the water and OH - Better access to the interlayer to transfer Na + and SO4 2- Replace them to further reduce the impurity Na and S content of the high-nickel ternary precursor.

[0091] It can be understood that if the concentration of lithium ions in the alkaline solution containing lithium is less than 2.5%, the concentration of lithium ions will be too low to fully and completely replace the sodium ions in the ternary lithium precursor; if the concentration of lithium ions in the alkaline solution containing lithium is greater than 15%, the concentration of lithium ions will be too high to cause Li + The ions are well inserted into the interlayer of the high-nickel ternary precursor to form too many intercalation compounds, resulting in more microcracks in the high-nickel ternary precursor and affecting the stability of the structure of the high-nickel ternary precursor. Therefore, in one embodiment, the mass percentage concentration of the lithium-containing alkaline solution is 2.5% to 15% to ensure that the lithium ion concentration of the lithium-containing alkaline solution is more appropriate, while satisfying that the lithium ions can fully and comprehensively replace the sodium ions in the ternary precursor, and also ensure the stability of the high-nickel ternary precursor structure finally prepared.

[0092] It can also be understood that if the temperature of the secondary hot alkali soaking operation is lower than 60°C or the time of the secondary hot alkali soaking operation is too short, the OH - It is not possible to enter the interlayer of the high-nickel ternary precursor and fully and completely replace SO4 2- If the temperature of the secondary hot alkali soaking operation is higher than 70℃ or the secondary hot alkali soaking operation time is too long, OH - The surface of the high-nickel ternary precursor will be dissolved too much, thus affecting the structural stability of the high-nickel ternary precursor finally prepared. Therefore, in one embodiment, the temperature of the secondary hot alkali soaking operation is controlled to be 60°C to 70°C, and the time of the secondary hot alkali soaking operation is 1h to 2h; in particular, the concentration of the alkaline solution containing lithium is used to ensure that the addition of OH - It can fully and completely replace the SO4 inside the crystal of the high-nickel ternary precursor 2-At the same time, it also ensures that the added lithium ions can enter the interlayer of the high-nickel ternary precursor more quickly, reliably and stably, which helps to quickly prepare a high-nickel ternary precursor with a stable structure and low sodium and sulfur content.

[0093] In one embodiment, the secondary hot alkali soaking operation time is 1h to 2h of warm soaking to ensure that the lithium ions and OH in the added lithium-containing alkaline solution are - It can enter the interlayer of the high-nickel ternary precursor relatively quickly, reliably and stably, which helps to quickly prepare a high-nickel ternary precursor with a stable structure and low sodium and sulfur content.

[0094] S107, subjecting the high nickel ternary precursor slurry C to ultrasonic vibration treatment, so that the ultrasonic vibration can generate a weak vibration force, which is conducive to the slow and reliable expansion and enlargement of the high nickel ternary precursor, that is, the secondary enlargement and swelling of the interlayer of the high nickel ternary precursor is achieved, thereby facilitating the water and OH - Better access to the interlayer to transfer Na + and SO4 2- The impurity Na and S content in the high-nickel ternary precursor can be replaced, thereby further reducing the content of impurities Na and S in the high-nickel ternary precursor; and the weak vibration force can effectively prevent the high-nickel ternary precursor, which has been swollen and enlarged, from developing severe cracks or easy falling off due to excessive ultrasonic vibration amplitude.

[0095] It can be understood that if the ultrasonic frequency of the ultrasonic vibration treatment is greater than 60KHz or the time of the ultrasonic vibration treatment is greater than 10min, the vibration force during the ultrasonic vibration treatment will be large, causing the high-nickel ternary precursor to be prone to severe cracks or fall off; if the ultrasonic frequency of the ultrasonic vibration treatment is less than 40KHz or the time of the ultrasonic vibration treatment is less than 5min, the vibration amplitude during the ultrasonic vibration treatment will be small and it will be impossible to achieve a more comprehensive entry of lithium ions into the interlayer replacement of sodium ions in the high-nickel ternary precursor. Therefore, in one embodiment, the ultrasonic frequency of the ultrasonic vibration treatment is 40KHz to 60KHz, and the time of the ultrasonic vibration treatment is 5min to 10min; to ensure that the amplitude of the ultrasonic vibration treatment is more appropriate, and the time of the vibration treatment is more appropriate, so as to ensure that the lithium ions can reliably, fully and comprehensively enter the interlayer of the high-nickel ternary precursor, which is helpful to prepare a high-nickel ternary precursor with a stable structure and a low sodium-sulfur content.

[0096] It should be noted that since the high-nickel ternary precursor has been initially expanded and enlarged, if the same duration as the expansion ultrasonic treatment is used, it is easy to cause the enlarged high-nickel ternary precursor to have serious cracks or fall off due to the long amplitude time. Therefore, in the present disclosure, the ultrasonic vibration treatment time is controlled to be significantly shorter than the expansion ultrasonic treatment time to avoid the problem of serious microcracks or falling off of the enlarged high-nickel ternary precursor due to the long vibration time.

[0097] It can also be understood that since the high-nickel ternary precursor has been initially swollen and enlarged, if the high-nickel ternary precursor slurry C is heated and ultrasonically vibrated at the same time, the enlarged high-nickel ternary precursor will have serious cracks or fall off. Therefore, in the present disclosure, the high-nickel ternary precursor slurry C is obtained by performing a secondary hot alkali soaking operation on the high-nickel ternary precursor bottom liquid B; then the high-nickel ternary precursor slurry C is subjected to ultrasonic vibration treatment; the step-by-step treatment of the secondary hot alkali soaking operation and the ultrasonic vibration treatment is achieved, effectively avoiding the problem of the enlarged high-nickel ternary precursor having serious microcracks or falling off due to the simultaneous heating and ultrasonic vibration treatment.

[0098] Specifically, in one of the embodiments, after the high-nickel ternary precursor base liquid B completes the secondary hot alkali insulation immersion operation, ultrasonic vibration treatment is performed to achieve a step-by-step treatment of the secondary hot alkali immersion operation and the ultrasonic vibration treatment.

[0099] S108, filtering the high-nickel ternary precursor slurry C treated with ultrasonic vibration to obtain a high-nickel ternary precursor filter residue.

[0100] It is understandable that due to the replacement of Na + 、SO4 2- It is usually dissolved in the high-nickel ternary precursor slurry C. When the high-nickel ternary precursor slurry C is filtered, the replaced Na + 、SO4 2- , thereby obtaining a high-nickel ternary precursor filter residue with low Na and S content.

[0101] S109, washing the high nickel ternary precursor residue with hot water for the first time to effectively remove the impurities Na on the surface of the high nickel ternary precursor. + 、SO4 2- , which is conducive to the preparation of a high-nickel ternary precursor with low Na and S content, qualified BET indicators and stable structure.

[0102] S110. Dry the high-nickel ternary precursor residue after the first hot water wash to obtain a high-nickel ternary precursor, so as to effectively remove the solvent of the high-nickel ternary precursor residue, thereby ensuring that a high-nickel ternary precursor with low Na and S content, qualified BET index and stable structure is prepared.

[0103] The above-mentioned method for removing sodium and sulfur from the high-nickel ternary precursor, through the coordinated use of swelling ultrasonic treatment, one hot alkali soaking operation, two hot alkali soaking operations and ultrasonic vibration treatment, enables the organic lithium swelling solution to achieve the initial swelling of the high-nickel ternary precursor, and achieves the effect of preliminary removal of Na and S from the high-nickel ternary precursor; it is conducive to the sodium-containing alkaline solution in the subsequent one hot alkali soaking operation to replace the SO4 inside the crystal of the high-nickel ternary precursor 2- , and is also beneficial to the subsequent secondary hot alkali soaking operation in the lithium-containing alkaline solution + Enter the interlayer of the high-nickel ternary precursor to replace Na + , in conjunction with the effect of ultrasonic vibration treatment, the secondary enlargement and swelling of the interlayer of the high-nickel ternary precursor is achieved, further reducing the impurity Na and S content of the high-nickel ternary precursor; and the sodium-containing alkaline solution can dissolve the surface and microcrack surface of the high-nickel ternary precursor in trace amounts, so as to form nickel, cobalt and manganese metal ions in the high-nickel ternary precursor slurry B, thereby providing sufficient metal ions for the subsequent repair of microcracks; the carboxyl and amino groups with strong coordination ability in the added aminocarboxylic acid complexing solution can form complexes with free nickel, cobalt and manganese metal ions, and then the generated complexes will react with OH in the first hot alkali soaking and the second hot alkali soaking operation. - A co-precipitation reaction occurs, so that the microcracks of the high-nickel ternary precursor are fully repaired and improved, thereby achieving the effect of repairing the microcracks of the high-nickel ternary precursor, ensuring that the BET index of the high-nickel ternary precursor is qualified, thereby ensuring the structural stability of the high-nickel ternary precursor, and thereby ensuring that safety problems such as structural collapse or short circuit are not prone to occur during the use of lithium-ion batteries.

[0104] It should be noted that the repair of microcracks in the high-nickel ternary precursor is mainly divided into two stages: after the metal ions are dissolved by the first hot alkali immersion operation, the carboxyl and amino groups can complex the free metal ions to form a complex, and then the complex will co-precipitate with the hydroxide ions to generate nickel cobalt manganese hydroxide precipitates, thereby achieving the main repair of the microcracks in the high-nickel ternary precursor; since a small amount of bottom liquid is retained in the high-nickel ternary precursor bottom liquid B during the second static separation, the complex containing nickel cobalt manganese metal ions remaining in the bottom liquid will co-precipitate with the hydroxide ions in the second hot alkali immersion to more fully repair the microcracks in the high-nickel ternary precursor, thereby achieving reinforcement repair of the microcracks in the high-nickel ternary precursor and more fully repairing the microcracks in the high-nickel ternary precursor.

[0105] The present disclosure also provides a high-nickel ternary precursor, which is prepared by the method for removing sodium and sulfur from the high-nickel ternary precursor described in any of the above embodiments.

[0106] It can be understood that the present invention achieves a more comprehensive removal of impurities Na and S in the high-nickel ternary precursor by sequentially subjecting the crude high-nickel ternary precursor product to swelling ultrasonic treatment, a first hot alkali soaking operation, a second hot alkali soaking operation, ultrasonic vibration treatment, a first hot water wash, filtration and drying operations, and ensures that the BET index of the prepared high-nickel ternary precursor is qualified and the structural stability is good.

[0107] In one embodiment, the BET index of the high nickel ternary precursor is in the range of 6.0 m 2 / g~7.0m 2 / g.

[0108] Some specific examples are given below, and if % is mentioned, it means percentage by weight. It should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial sources unless otherwise specified.

[0109] Example 1

[0110] Obtaining S1 high nickel ternary precursor crude product:

[0111] S11 mother liquor removal:

[0112] Take 100 mL of the newly produced NCM811 high-nickel ternary precursor slurry in the reactor, filter and remove the mother liquor in a suction filtration bottle, and separate the solid high-nickel ternary precursor crude product; wherein the particle size of NCM811 is 10.35 μm;

[0113] S12 second hot water wash:

[0114] Add 100 mL of hot pure water at 65° C. to the suction filtration bottle of S11 to wash the solid high-nickel ternary precursor crude product for 2 min, continue to filter until it is dried to obtain a solid high-nickel ternary precursor crude product, and separate the dried high-nickel ternary precursor crude product from the filter paper into a beaker;

[0115] S2 Swelling Ultrasonic Treatment:

[0116] Add 50 mL of 65°C 5% n-butyl lithium solution (solute is n-butyl lithium, solvent is ether) to the beaker of S12, stir evenly to make slurry, and place the beaker in an ultrasonic machine for continuous ultrasonic immersion for 1 hour, the ultrasonic frequency is 53KHz, the temperature is 30°C, and a high-nickel ternary precursor slurry A is obtained;

[0117] S3 first static separation:

[0118] After completing step S2, the high-nickel ternary precursor slurry A is subjected to a first standing separation, the first standing separation time is 15 minutes, and the upper layer of the solvent of the high-nickel ternary precursor slurry A is poured out, and a small amount of bottom liquid is retained to obtain a high-nickel ternary precursor bottom liquid A;

[0119] S4 one-time hot alkali soaking operation:

[0120] Add 65°C NaOH & EDTA mixed solution to the beaker of S3, stir to make slurry, and place the beaker in a constant temperature water bath at 65°C for 1 hour to keep warm; obtain high nickel ternary precursor slurry B; wherein, the NaOH & EDTA mixed solution is prepared by dropping 20ml of 2.6g / L EDTA solution into 100mL 65°C NaOH solution with a concentration of 2.5%, and mix well.

[0121] S5 second static separation:

[0122] The high nickel ternary precursor slurry B of S4 is subjected to a second static separation, the second static separation time is 15 minutes, and the upper layer of the solvent of the high nickel ternary precursor slurry B is poured out, and a small amount of bottom liquid is retained to obtain a high nickel ternary precursor bottom liquid B;

[0123] S6 secondary hot alkali soaking operation:

[0124] Add 100 mL of 10% LiOH alkaline solution at 65° C. to the beaker of S5, and place the beaker in a constant temperature water bath at 65° C. for 1 h to obtain a high-nickel ternary precursor slurry C;

[0125] S7 Ultrasonic Vibration Treatment:

[0126] After the heat preservation in step S6 is completed, the beaker is placed in an ultrasonic machine for continuous ultrasonication for 5 minutes at a frequency of 53 KHz;

[0127] S8 Filtration:

[0128] The high-nickel ternary precursor slurry C of step S7 is placed in a suction filtration bottle for suction filtration to obtain a high-nickel ternary precursor residue;

[0129] S9 first hot water wash:

[0130] Add 200 mL of hot pure water at 65°C to the filtration bottle of S8 for the first wash for 4 min until the filter is dry;

[0131] S10 Drying:

[0132] The high-nickel ternary precursor residue of S9 is dried at 120° C. for 2 hours to obtain a high-nickel ternary precursor.

[0133] Example 2

[0134] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 25% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0135] Example 3

[0136] The difference from Example 2 is that the 2.5% concentration of 100 mL 65°C NaOH solution and 2.6 g / L EDTA solution of S4 are replaced with 30% concentration of 100 mL 65°C NaOH solution and 2.9 g / L EDTA solution, and the rest remain unchanged.

[0137] Example 4

[0138] The difference from Example 3 is that the 1-hour heat preservation soaking of S4 is replaced by 3-hour heat preservation soaking, and the 10% concentration 100 mL LiOH alkaline solution of S6 is replaced by 2.5% concentration 100 mL LiOH alkaline solution, and the rest remains unchanged.

[0139] Example 5

[0140] The difference from Example 4 is that the 30% concentration of 100mL65℃NaOH solution and 2.9g / L ethylenediaminetetraacetic acid solution in S4 are replaced by 30% concentration of 100mL65℃NaOH solution and 3.2g / L ethylenediaminetetraacetic acid solution, the 2.5% concentration of 100mL LiOH alkaline solution in S6 is replaced by 10% concentration of 100mL LiOH alkaline solution, and the beaker being kept warm in a constant temperature water bath at 65℃ for 1h in S6 is replaced by the beaker being kept warm in a constant temperature water bath at 65℃ for 3h, and the rest remains unchanged.

[0141] Comparative Example 1

[0142] The difference from Example 1 is that the comparative example 1 omits steps S2, S3, S6, and S7, and the steps of the comparative example 1 include:

[0143] S1 The acquisition of the crude product of high-nickel ternary precursor is the same as in Example 1;

[0144] S4 one-time hot alkali soaking operation: add 100mL65℃NaOH solution at 65℃ and 2.5% concentration to the crude product of high-nickel ternary precursor and soak for 900s; after soaking, complete solid-liquid separation in the suction filtration bottle until filtered dry; then continue to pour 100mL65℃NaOH solution at 65℃ and 2.5% concentration into the suction filtration bottle for direct alkali washing until filtered dry to obtain high-nickel ternary precursor residue;

[0145] S9 first hot water washing, the same as in Example 1;

[0146] S10 drying, the same as in Example 1, to obtain a high-nickel ternary precursor;

[0147] It can be seen that Comparative Example 1 adopts the process of alkali soaking + alkali washing + water washing.

[0148] Comparative Example 2

[0149] The difference from Example 1 is that the step S7 is omitted in Comparative Example 2, and the steps S4 and S6 are different. The steps of Comparative Example 2 include:

[0150] Steps S1 to S3 are the same as those in Example 1;

[0151] S4 one-time hot alkali soaking operation: add 100 mL of 65°C NaOH solution with a concentration of 2.5% at 65°C to the beaker of S3, stir and slurry, and place the beaker in a constant temperature water bath at 65°C for 1 hour to obtain high nickel ternary precursor slurry B;

[0152] S5 second static separation, the same as in Example 1;

[0153] S6 alkali washing operation: the high nickel ternary precursor bottom liquid B in step S5 is placed in a suction filtration bottle, and then 100 mL of 65°C NaOH solution with a concentration of 2.5% at 65°C is poured in for direct alkali washing until it is filtered dry to obtain a high nickel ternary precursor filter residue;

[0154] S9 first hot water washing, the same as in Example 1;

[0155] S10 drying, the same as in Example 1;

[0156] It can be seen that Comparative Example 2 adopts the process of swelling ultrasound + one hot alkali soaking + alkali washing + water washing.

[0157] The Li, Na, S and BET of the high nickel ternary precursors prepared in the above Examples 1 to 5 and Comparative Examples 1 to 2 were tested to obtain the experimental data in Table 1 below:

[0158] Table 1

[0159]

[0160]

[0161]

[0162] From Comparative Examples 1 to 2, it can be seen that the Na and S contents of Comparative Example 2 are lower than those of Comparative Example 1 which is not soaked in n-butyl lithium solution, and BET increases slightly. This is because the interlayer spacing of the high nickel ternary precursor increases after soaking in n-butyl lithium solution, so that more Na can be replaced during alkali washing and water washing in Comparative Example 2. + and SO4 2- .

[0163] It can be seen from Examples 1 to 5 and Comparative Examples 1 to 2 that the high nickel ternary precursors of Examples 1 to 5 can better replace the Na between the layers of the high nickel ternary precursors under the dual swelling effect of immersion in n-butyl lithium solution and LiOH solution. + and SO4 2- , making the Na and S contents of Examples 1 to 5 significantly lower than those of Comparative Examples 1 to 2, and the dual swelling effect of n-butyl lithium solution and LiOH solution can increase the BET of the high-nickel ternary precursor, making the BET of Examples 1 to 5 significantly higher than that of Comparative Examples 1 to 2.

[0164] from Figure 2 It can be seen that since Comparative Example 1 only uses alkali immersion and does not undergo swelling ultrasonic treatment, the sheet layer of the high nickel ternary precursor of Comparative Example 1 is denser ( Figure 2 Figure left); from Figures 3 to 5 It can be seen that, since Examples 1, 3 and 5 are subjected to swelling ultrasonic treatment, one hot alkali soaking and two hot alkali soaking operations, the sheets of the high nickel ternary precursors of Examples 1, 3 and 5 are more loose and have higher BET. In addition, since a mixed solution of NaOH & EDTA is used in Examples 1, 3 and 5, the amino and carboxyl groups of EDTA can form complexes with free nickel, cobalt and manganese metal ions, and then the complexes can react with OH in the one hot alkali soaking and the two hot alkali soaking. - The co-precipitation reaction significantly reduced the number of microcracks in the high-nickel ternary precursor and significantly improved the cracking phenomenon, indicating that the use of a mixed solution containing a complexing liquid for a single hot alkali soak combined with a secondary hot alkali soak is beneficial to better repair the microcracks of the high-nickel ternary precursor, thereby ensuring the stability of the structure of the prepared high-nickel ternary precursor.

[0165] It can be seen from Examples 1 and 2 that the comprehensive index of Example 2 after swelling and ultrasonic treatment with 25% n-butyl lithium solution is better than that of Example 1.

[0166] From Example 2 and Example 3, it can be seen that although Example 3 was soaked once in a hot alkali mixture of 30% NaOH & 2.9 g / L EDTA, the indicators of the two are similar, and Na and BET are in line with the indicator range of NCM811 products on the market.

[0167] Example 6

[0168] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced by a 10% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0169] Example 7

[0170] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 15% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0171] Example 8

[0172] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 20% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0173] Example 9

[0174] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 25% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0175] Example 10

[0176] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 30% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0177] Comparative Example 3

[0178] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 2.5% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0179] Comparative Example 4

[0180] The difference from Example 1 is that the 5% n-butyllithium solution in S2 is replaced with a 35% n-butyllithium solution (the solute is n-butyllithium and the solvent is ether), and the rest remains unchanged.

[0181] The high nickel ternary precursors prepared in the above-mentioned Example 1, Examples 6 to 10 and Comparative Examples 3 to 4 were subjected to Na, S and BET tests to obtain the data in Table 2.

[0182] Table 2

[0183]

[0184]

[0185] It can be seen from Table 2 that when the mass percentage concentration of the organic lithium swelling solution is between 5% and 30%, it is beneficial to remove the Na and S contents in the high-nickel ternary precursor and increase the BET index.

[0186] Embodiment 11

[0187] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 5% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0188] Example 12

[0189] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 10% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0190] Example 13

[0191] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 15% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0192] Embodiment 14

[0193] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 20% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0194] Embodiment 15

[0195] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 30% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0196] Comparative Example 5

[0197] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 2.0% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0198] Comparative Example 6

[0199] The difference from Example 1 is that the 2.5% concentration 100 mL 65° C. NaOH in step S4 is replaced with 35% concentration 100 mL 65° C. NaOH, and the rest remains unchanged.

[0200] The high nickel ternary precursors prepared in Example 1, Examples 11 to 15 and Comparative Examples 5 to 6 were subjected to Na, S, and BET tests to obtain the data in Table 3:

[0201] Table 3

[0202]

[0203]

[0204] It can be seen from Table 3 that when the mass percentage concentration of the sodium-containing alkaline solution is between 2.5% and 30%, the Na and S removal effects can be achieved. When the mass percentage concentration is 2.0%, the S removal effect is poor. When the mass percentage concentration is 35%, the Na impurity increases. The Na impurity increases with the increase of the NaOH solution concentration.

[0205] Comparative Example 7

[0206] The difference from Example 1 is that the heat preservation soaking time of S4 for 1h is replaced by 0h, and the rest remains unchanged.

[0207] Example 16

[0208] The difference from Example 1 is that the heat preservation soaking time of S4 for 1 hour is replaced by 2 hours, and the rest remains unchanged.

[0209] Comparative Example 8

[0210] The difference from Example 1 is that the heat preservation soaking time of S4 for 1 hour is replaced by 3 hours, and the rest remains unchanged.

[0211] The high nickel ternary precursors prepared in Example 1, Comparative Examples 7-8, and Example 16 were subjected to Na, S, and BET tests to obtain the experimental data in Table 4:

[0212] Table 4

[0213]

[0214]

[0215] It can be seen from Table 4 that when the time of a hot alkali immersion operation is 1h to 2h, it is beneficial to remove the Na and S contents in the high-nickel ternary precursor and increase the BET index.

[0216] Comparative Example 9

[0217] The difference from Example 1 is that 100 mL of the 10% concentration LiOH solution of S6 is replaced with 100 mL of the 2.5% concentration NaOH solution, and the rest remains unchanged.

[0218] Embodiment 17

[0219] The difference from Example 1 is that 100 mL of the 10% LiOH solution of S6 is replaced with 100 mL of the 2.5% LiOH solution, and the rest remains unchanged.

[0220] Embodiment 18

[0221] The difference from Example 1 is that 100 mL of the 10% concentration LiOH solution of S6 is replaced with 100 mL of the 5% concentration LiOH solution, and the rest remains unchanged.

[0222] Embodiment 19

[0223] The difference from Example 1 is that 100 mL of the 10% concentration LiOH solution of S6 is replaced with 100 mL of the 15% concentration LiOH solution, and the rest remains unchanged.

[0224] Comparative Example 10

[0225] The difference from Example 1 is that 100 mL of the 10% LiOH solution of S6 is replaced with 100 mL of the 2.0% LiOH solution, and the rest remains unchanged.

[0226] Comparative Example 11

[0227] The difference from Example 1 is that 100 mL of the 10% concentration LiOH solution of S6 is replaced with 100 mL of the 20% concentration LiOH solution, and the rest remains unchanged.

[0228] The high nickel ternary precursors prepared in Example 1, Comparative Examples 9-11, and Examples 17-19 were subjected to Li, Na, S, and BET tests to obtain the experimental data in Table 5:

[0229] Table 5

[0230]

[0231]

[0232] It can be seen from Table 5 that when the mass percentage concentration of the lithium-containing alkaline solution is 2.5% to 15%, it is beneficial to remove the Na and S content in the high-nickel ternary precursor. It can be seen from Comparative Example 9 and Example 17 that the NaOH added in Comparative Example 9 will introduce new Na impurities, causing the Na removal index of Comparative Example 9 to be unqualified.

[0233] Comparative Example 12

[0234] The difference from Example 1 is that the insulation time of S6 for 1h is replaced by 0h, and the rest remains unchanged.

[0235] Embodiment 20

[0236] The difference from Example 1 is that the insulation time of S6 for 1 h is replaced by 2 h, and the rest remains unchanged.

[0237] Comparative Example 13

[0238] The difference from Example 1 is that the insulation time of S6 for 1 h is replaced by 3 h, and the rest remains unchanged.

[0239] The Li, Na, S and BET of the high nickel ternary precursor prepared in the above Example 1, Comparative Examples 12-13 and Example 20 were tested to obtain the experimental data in Table 6 below:

[0240] Table 6

[0241]

[0242]

[0243] It can be seen from Table 6 that when the secondary hot alkali immersion operation time is 1h to 2h, it is beneficial to remove the Na and S contents in the high-nickel ternary precursor and increase the BET index.

[0244] Combination Figures 2 to 5 It can be seen that the NaOH & EDTA mixed solution added in Examples 1, 3, and 5 can react with the OH solution in the first hot alkali soaking and the second hot alkali soaking. - A coprecipitation reaction occurs to better repair the microcracks of the high-nickel ternary precursor, thereby ensuring the stability of the structure of the prepared high-nickel ternary precursor. Among them, the comprehensive index of Example 3 is the best.

[0245] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.

Claims

1. A method for removing sodium and sulfur from a high-nickel ternary precursor, characterized in that: The steps include: Obtaining a high-nickel ternary precursor crude product; The high-nickel ternary precursor crude product is placed in an organic lithium swelling solution for swelling ultrasonic treatment to obtain a high-nickel ternary precursor slurry A; The high-nickel ternary precursor slurry A is subjected to a first static separation to obtain a high-nickel ternary precursor bottom liquid A; The high-nickel ternary precursor base liquid A is subjected to a hot alkali soaking operation to obtain a high-nickel ternary precursor slurry B, wherein the solution during the hot alkali soaking operation is a mixture of a sodium-containing alkaline solution and an aminocarboxylic acid complexing solution; The high-nickel ternary precursor slurry B is subjected to a second static separation to obtain a high-nickel ternary precursor bottom liquid B; The high-nickel ternary precursor bottom solution B is subjected to a secondary hot alkali soaking operation to obtain a high-nickel ternary precursor slurry C, wherein the solution during the secondary hot alkali soaking operation is an alkaline solution containing lithium; Performing ultrasonic vibration treatment on the high-nickel ternary precursor slurry C; The high-nickel ternary precursor slurry C treated with ultrasonic vibration is filtered to obtain a high-nickel ternary precursor filter residue; Performing a first hot water wash on the high-nickel ternary precursor residue; The high-nickel ternary precursor filter residue after the first hot water washing is dried to obtain a high-nickel ternary precursor.

2. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 1, characterized in that: The preparation of the mixed solution of the sodium-containing alkaline solution and the aminocarboxylic acid complex solution comprises the following steps: Obtaining the sodium-containing alkaline solution with a mass percentage concentration of 2.5% to 30%; The aminocarboxylic acid complex liquid with a concentration of 2.5 g / L to 3.5 g / L is added to the sodium-containing alkaline solution to obtain a mixed solution of the sodium-containing alkaline solution and the aminocarboxylic acid complex liquid.

3. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 2, characterized in that: The sodium-containing alkaline solution includes at least one of a sodium hydroxide solution, a sodium carbonate solution and a sodium bicarbonate solution; and / or, The aminocarboxylic acid complexing liquid includes at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid and hydroxyethylethylenediaminetriacetic acid.

4. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 1, characterized in that: The mass percentage concentration of the lithium-containing alkaline solution is 2.5% to 15%.

5. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 1, characterized in that: The high-nickel ternary precursor is NCM811, and the average particle size of the high-nickel ternary precursor is greater than 10 μm.

6. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 1, characterized in that: The mass percentage concentration of the organic lithium swelling solution is 5% to 30%.

7. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 6, characterized in that: The solute of the organic lithium swelling solution includes at least one of n-butyl lithium, isobutyl lithium, tert-butyl lithium, sec-butyl lithium and methyl lithium; and / or, The solvent of the organic lithium swelling solution includes at least one of ethyl ether, diethylene glycol dimethyl ether, hexane and petroleum ether.

8. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 1, characterized in that: The ultrasonic frequency of the swelling ultrasonic treatment is 40KHz to 60KHz, the time of the swelling ultrasonic treatment is 0.5h to 1h; the temperature of the swelling ultrasonic treatment is 20°C to 30°C; and / or, The temperature of the hot alkali soaking operation is 60°C to 70°C, and the time of the hot alkali soaking operation is 1h to 2h; and / or, The temperature of the secondary hot alkali soaking operation is 60°C to 70°C, and the time of the secondary hot alkali soaking operation is 1h to 2h; and / or, The ultrasonic frequency of the ultrasonic vibration treatment is 40KHz to 60KHz, and the time of the ultrasonic vibration treatment is 5min to 10min; and / or, The temperature of the first hot water washing is 60°C to 70°C.

9. The method for removing sodium and sulfur from a high-nickel ternary precursor according to claim 1, characterized in that: Before the step of obtaining the high-nickel ternary precursor crude product, the method further comprises the following steps: The mother liquor is subjected to a removal operation to obtain a solid high-nickel ternary precursor crude product; washing the solid high-nickel ternary precursor crude product with hot water for a second time; The solid high-nickel ternary precursor crude product that has been washed with hot water for the second time is filtered to obtain the high-nickel ternary precursor crude product.

10. A high-nickel ternary precursor, characterized in that: The product is prepared by the method for removing sodium and sulfur from a high-nickel ternary precursor as described in any one of claims 1 to 9.

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