Ternary precursor with high tap density and method for preparing the same

Abstract

Disclosed herein are a ternary precursor with a high tap density and a method for preparing same. The method comprises the following steps: (1) adding a silicon dioxide emulsion into an alkaline substrate solution to give a mixed solution; (2) adding a mixed nickel-cobalt-manganese salt solution, a precipitant, a complexing agent, and a surfactant; (3) conducting solid-liquid separation to give a solid material, and drying and crushing to give a crushed material; (4) mixing the crushed material with the alkaline substrate solution and the surfactant; (5) repeating step (2); and (6) conducting solid-liquid separation to give a solid material, and washing and drying the solid material to give the ternary precursor with a high tap density. The precursor particle prepared according to the method has a higher tap density, and can provide excellent cycle performance for the positive electrode material.

Description

A high tap density ternary precursor and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of lithium battery positive electrode materials, and in particular relates to a high tap density ternary precursor and a preparation method thereof. Background Art

[0002] Since the commercialization of lithium-ion batteries, their applications have gradually expanded from the 3C electronics field to the power sector. However, at the same time, people's requirements for lithium-ion battery safety, energy density, and service life have become increasingly higher. In the battery manufacturing process, the positive electrode material is the most important component, which determines the battery's performance and application areas to a certain extent.

[0003] Ternary cathode materials have gradually become mainstream products on the market due to their high energy density advantages. In industry, the co-precipitation method is commonly used to first prepare a nickel-cobalt-manganese hydroxide precursor, and then the precursor is mixed with a lithium source and sintered to prepare the cathode material. As the main raw material of the ternary cathode material, the structure and performance of the ternary precursor directly determine the structure and performance of the ternary cathode material. It is well known that the cathode material can inherit the morphology and structural characteristics of the precursor. The various properties of the cathode material depend to a large extent on the physical and chemical properties of its precursor. The technical content of the precursor preparation accounts for more than 60% of the technical content of the entire ternary material. Therefore, the structure and preparation process of the precursor have a vital impact on the performance of the cathode material.

[0004] At present, co-precipitation is the mainstream preparation method for precursor materials. It can accurately control the content of each component and achieve atomic-level mixing of components. By adjusting synthesis process parameters such as solution concentration, pH value, reaction time, reaction temperature, and stirring speed, materials with different particle size, morphology, density, and degree of crystallinity can be prepared.

[0005] The co-precipitation method is currently the most widely used method and its industrialization is relatively mature. However, when preparing precursor materials, the existing co-precipitation method has a problem. During the co-precipitation, primary particles are rapidly formed and agglomerated, resulting in a fast precipitation rate. As a result, the primary particles are generally small in size, with low crystallinity. The primary particles are not dense enough, the overall density of the precursor is low, and the tap density is low, which affects the cycle performance of the positive electrode material prepared by subsequent sintering.

[0006] Summary of the Invention

[0007] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention provides a high-tap-density ternary precursor and a method for preparing the same. These precursor particles can be prepared to produce coarse and dense precursor particles with a high tap density, thereby improving the cycling performance of the subsequently sintered cathode material.

[0008] The above technical objectives of the present invention are achieved through the following technical solutions:

[0009] A method for preparing a ternary precursor with high tap density comprises the following steps:

[0010] (1) adding a silica emulsion to an alkaline base liquid under stirring to form a mixed liquid;

[0011] (2) adding a mixed salt solution of nickel, cobalt and manganese metal ions, a precipitant, a complexing agent and a surfactant to the mixed solution of step (1) to react so that the D50 of the material in the mixed solution reaches 1.0-3.0 μm;

[0012] (3) performing solid-liquid separation on the material of step (2) to obtain a solid material, drying the solid material, and then crushing it to obtain a crushed material;

[0013] (4) mixing the crushed material obtained in step (3) with an alkaline base liquid and a surfactant;

[0014] (5) adding a mixed salt solution of nickel, cobalt and manganese metal ions, a precipitant, a complexing agent and a surfactant to the mixed solution of step (4) to react so that the D50 of the material in the mixed solution reaches 5.0-15.0 μm;

[0015] (6) The material of step (5) is subjected to solid-liquid separation to obtain a solid material, and the solid material is washed and dried to obtain a ternary precursor with a high tap density.

[0016] Preferably, the alkaline base liquid is a mixture of sodium hydroxide and ammonia water, the pH value of the alkaline base liquid is 10.0-11.0, and the ammonia concentration is 2.0-10.0 g / L.

[0017] Preferably, the mass concentration of silicon dioxide in the mixed solution of step (1) is 1-3%, and the particle size of silicon dioxide is 1-100 nm.

[0018] Preferably, the total concentration of nickel, cobalt and manganese metal ions in the nickel, cobalt and manganese metal ion mixed salt solution is 1.0-2.5 mol / L.

[0019] Preferably, the precipitant is a sodium hydroxide solution with a concentration of 4.0-8.0 mol / L.

[0020] Preferably, the complexing agent is aqueous ammonia with a concentration of 6.0-12.0 mol / L.

[0021] Preferably, the surfactant is at least one of an aqueous solution of alkylbenzenesulfonate, an aqueous solution of alkylnaphthalenesulfonate, and an aqueous solution of alkanesulfonate, and the concentration of the surfactant is 0.1-2 mol / L.

[0022] Preferably, in step (1), the silicon dioxide emulsion is ultrasonically dispersed for 20-30 minutes before adding the alkaline base liquid.

[0023] Preferably, the particle size D50 of the crushed material obtained in step (3) is 100-500 nm.

[0024] Preferably, in step (2) and step (5), the nickel-cobalt-manganese metal ion mixed salt solution, precipitant, complexing agent and surfactant are added in parallel, and during the addition process, the pH of the mixed solution is controlled to be 10.0-11.0, the ammonia concentration is 2.0-10.0 g / L, and the flow rate of the surfactant is controlled to be 0.1-1 times the flow rate of the mixed salt solution.

[0025] Preferably, the reaction temperature in step (2) and step (5) is 45-65°C.

[0026] Preferably, a method for preparing a ternary precursor with high tap density comprises the following steps:

[0027] (1) According to the element molar ratio Ni:Co:Mn=1-ab:a:b, soluble salts of nickel, cobalt, and manganese are selected as raw materials to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 1.0-2.5 mol / L;

[0028] (2) preparing a sodium hydroxide solution with a concentration of 4.0-8.0 mol / L as a precipitant;

[0029] (3) preparing ammonia water with a concentration of 6.0-12.0 mol / L as a complexing agent;

[0030] (4) preparing a surfactant aqueous solution with a concentration of 0.1-2 mol / L, wherein the surfactant is alkylbenzene sulfonate, alkylnaphthalene sulfonate, or alkane sulfonate;

[0031] (5) adding alkaline bottom liquid to the reactor until it covers the bottom stirring paddle and starting stirring. The alkaline bottom liquid is a mixture of sodium hydroxide and ammonia water. The pH value of the alkaline bottom liquid is 10.0-11.0, and the ammonia concentration is 2.0 g / L-10.0 g / L;

[0032] (6) adding a silica emulsion dispersed by ultrasonication for 20-30 minutes to the alkaline base solution so that the mass concentration of silica in the alkaline base solution is 1-3% and the particle size of silica is 1-100 nm;

[0033] (7) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) into a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 45-65° C., the pH to be 10.0-11.0, and the ammonia concentration to be 2.0-10.0 g / L; and controlling the flow rate of the surfactant to be 0.1-1 times the flow rate of the mixed salt solution;

[0034] (8) When the D50 of the material in the reactor is detected to reach 1.0-3.0 μm, the feeding is stopped;

[0035] (9) The material in the kettle is subjected to solid-liquid separation to obtain a solid material, which is dried and then pulverized using a jet mill. The particle size D50 of the pulverized material is 100-500 nm;

[0036] (10) Add the crushed material to the reactor, add the bottom liquid until it covers the bottom stirring paddle, and start stirring. The bottom liquid is a mixture of sodium hydroxide, ammonia water and surfactant. The pH value of the bottom liquid is 10.0-11.0, the ammonia concentration is 2.0-10.0 g / L, and the surfactant concentration is 2 mol / L;

[0037] (11) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) into a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 45-65° C., the pH to be 10.0-11.0, and the ammonia concentration to be 2.0-10.0 g / L; and controlling the flow rate of the surfactant to be 0.1-1 times the flow rate of the mixed salt solution;

[0038] (12) When the D50 of the material in the reactor is detected to reach 5.0-15.0 μm, the feeding is stopped;

[0039] (13) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0040] (14) The solid material is washed, dried, sieved, and demagnetized to obtain a ternary precursor with a high tap density.

[0041] A ternary precursor with high tap density is prepared by the preparation method described above.

[0042] Preferably, the chemical formula of the high tap density ternary precursor is Ni 1-a-b Co a Mn b(OH)2·xSiO2, where 0<a<1, 0<b<1, is a secondary particle agglomerated by primary particles. The primary particles are block-shaped cubes, the particle size of the primary particles is 0.1-5.0μm (1.0-3.0μm in the preparation method), and the particle size of the agglomerated secondary particles is 5.0-15.0μm.

[0043] The beneficial effects of the present invention are:

[0044] The present invention adds a silica emulsion to an alkaline bottom liquid and adopts a surfactant to carry out a coprecipitation reaction. The silica particles play a role of steric hindrance, can effectively isolate the primary particles generated by the reaction, slow down the agglomeration of the primary particles, and make the primary particles gradually grow. The surfactant plays a role of growth induction, promotes the growth of the primary particle crystals, and through the coordinated control of low pH, enables the primary particles to grow slowly, with better crystallinity. At the same time, further, the effective isolation of silica makes the material agglomeration not tight enough, which is conducive to subsequent air flow crushing. After air flow crushing, a crushed material similar to the primary particles is produced, and it is added to the reactor to continue to grow, so that the primary particles obtained are relatively dense and the particle size is relatively coarse block cubes. Its dense crystallization degree further improves the tap density of the material, the secondary growth of the particle size, and further improves the cycle performance of the subsequent sintered positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] FIG1 is a SEM image of Example 1 of the present invention. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to specific embodiments.

[0047] Example 1

[0048] A method for preparing a ternary precursor with high tap density comprises the following steps:

[0049] (1) According to the element molar ratio of Ni:Co:Mn=6:2:2, nickel sulfate, cobalt sulfate, and manganese sulfate were selected as raw materials to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 1.5 mol / L;

[0050] (2) preparing a sodium hydroxide solution with a concentration of 6.0 mol / L as a precipitant;

[0051] (3) Prepare 8.0 mol / L ammonia water as a complexing agent;

[0052] (4) preparing an aqueous solution of sodium dodecylbenzenesulfonate surfactant with a concentration of 1 mol / L;

[0053] (5) Adding a bottom liquid to the reactor until it covers the bottom stirring paddle, and starting stirring. The bottom liquid is a mixture of sodium hydroxide and ammonia water, the pH value of the bottom liquid is 10.5, and the ammonia concentration is 6.0 g / L;

[0054] (6) adding a silica emulsion dispersed by ultrasonication for 25 minutes to the base liquid so that the mass concentration of silica in the base liquid is 2% and the particle size of silica is 1-100 nm;

[0055] (7) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) to a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 55° C., the pH to be 10.5, and the ammonia concentration to be 6 g / L; and controlling the flow rate of the surfactant to be 0.5 times the flow rate of the mixed salt solution;

[0056] (8) When the D50 of the material in the reactor is detected to reach 2.0 μm, the feeding is stopped;

[0057] (9) The material in the kettle is subjected to solid-liquid separation to obtain a solid material. After the solid material is dried, it is crushed using a jet mill. The particle size D50 of the material after crushing is 320 nm;

[0058] (10) Add the crushed material into the reactor, add the bottom liquid until it covers the bottom stirring paddle, and start stirring. The bottom liquid is a mixture of sodium hydroxide, ammonia water and surfactant. The pH value of the bottom liquid is 10.5, the ammonia concentration is 6.0 g / L, and the surfactant concentration is 2 mol / L;

[0059] (11) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) into a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 55° C., the pH to be 10.5, and the ammonia concentration to be 6.0 g / L; and controlling the flow rate of the surfactant to be 0.5 times the flow rate of the mixed salt solution;

[0060] (12) When the D50 of the material in the reactor is detected to reach 10.5 μm, the feeding is stopped;

[0061] (13) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0062] (14) The solid material is washed and dried, and then sieved and demagnetized in sequence to obtain a ternary precursor with a high tap density.

[0063] A high tap density ternary precursor is prepared by the above preparation method, and its general chemical formula is Ni 0.6 Co 0.2 Mn 0.2(OH)2·xSiO2 is a secondary particle formed by the agglomeration of primary particles. The primary particles are blocky cubes with a particle size of 0.1-5.0 μm and agglomerated secondary particles with a particle size of 10.5 μm. The SEM image of the high tap density ternary precursor is shown in Figure 1.

[0064] Example 2

[0065] A method for preparing a ternary precursor with high tap density comprises the following steps:

[0066] (1) According to the element molar ratio of Ni:Co:Mn=8:1:1, nickel chloride, cobalt chloride, and manganese chloride were selected as raw materials to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 1.0 mol / L;

[0067] (2) preparing a sodium hydroxide solution with a concentration of 4.0 mol / L as a precipitant;

[0068] (3) Prepare 6.0 mol / L ammonia water as a complexing agent;

[0069] (4) preparing an aqueous solution of sodium dodecylnaphthalenesulfonate surfactant at a concentration of 0.1 mol / L;

[0070] (5) Adding a bottom liquid to the reactor until it covers the bottom stirring paddle, and starting stirring. The bottom liquid is a mixture of sodium hydroxide and ammonia water, with a pH value of 10.0 and an ammonia concentration of 2.0 g / L.

[0071] (6) adding a silica emulsion dispersed by ultrasonication for 20 minutes to the base liquid so that the mass concentration of silica in the base liquid is 1% and the particle size of silica is 1-100 nm;

[0072] (7) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) to a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 45° C., the pH to be 10.0, and the ammonia concentration to be 2.0 g / L; and controlling the flow rate of the surfactant to be 0.1 times the flow rate of the mixed salt solution;

[0073] (8) When the D50 of the material in the reactor is detected to reach 1.0 μm, the feeding is stopped;

[0074] (9) The material in the kettle is subjected to solid-liquid separation to obtain a solid material. After the solid material is dried, it is crushed using a jet mill. The particle size D50 of the material after crushing is 135 nm;

[0075] (10) Add the crushed material into the reactor, add the bottom liquid until it covers the bottom stirring paddle, and start stirring. The bottom liquid is a mixture of sodium hydroxide, ammonia water and surfactant. The pH value of the bottom liquid is 10.0, the ammonia concentration is 2.0 g / L, and the surfactant concentration is 2 mol / L;

[0076] (11) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) into a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 45° C., the pH to be 10.0, and the ammonia concentration to be 2.0 g / L; and controlling the flow rate of the surfactant to be 0.1 times the flow rate of the mixed salt solution;

[0077] (12) When the D50 of the material in the reactor is detected to reach 5.0 μm, the feeding is stopped;

[0078] (13) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0079] (14) The solid material is washed and dried, and then sieved and demagnetized in sequence to obtain a ternary precursor with a high tap density.

[0080] A high tap density ternary precursor is prepared by the above preparation method, and its general chemical formula is Ni 0.8 Co 0.1 Mn 0.1 (OH)2·xSiO2 is a secondary particle agglomerated by primary particles. The primary particles are blocky cubes with a particle size of 0.1-5.0 μm. The particle size of the agglomerated secondary particles is 5.0 μm.

[0081] Example 3

[0082] A method for preparing a ternary precursor with high tap density comprises the following steps:

[0083] (1) nickel nitrate, cobalt nitrate, and manganese nitrate were selected as raw materials according to the element molar ratio of Ni:Co:Mn=5:2:3 to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 2.5 mol / L;

[0084] (2) preparing a sodium hydroxide solution with a concentration of 8.0 mol / L as a precipitant;

[0085] (3) Prepare ammonia water with a concentration of 12.0 mol / L as a complexing agent;

[0086] (4) preparing a 2 mol / L aqueous solution of sodium lauryl sulfate surfactant;

[0087] (5) Adding a bottom liquid to the reactor until it covers the bottom stirring paddle, and starting stirring. The bottom liquid is a mixture of sodium hydroxide and ammonia water, the pH value of the bottom liquid is 11.0, and the ammonia concentration is 10.0 g / L;

[0088] (6) adding a silica emulsion dispersed by ultrasonication for 30 minutes to the base liquid so that the mass concentration of silica in the base liquid is 3% and the particle size of silica is 1-100 nm;

[0089] (7) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) to a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 65° C., the pH to be 11.0, and the ammonia concentration to be 10.0 g / L; and controlling the flow rate of the surfactant to be 1 times the flow rate of the mixed salt solution;

[0090] (8) When the D50 of the material in the reactor is detected to reach 3.0 μm, the feeding is stopped;

[0091] (9) The material in the kettle is subjected to solid-liquid separation to obtain a solid material. After the solid material is dried, it is crushed using a jet mill. The particle size D50 of the material after crushing is 470 nm;

[0092] (10) Add the crushed material into the reactor, add the bottom liquid until it covers the bottom stirring paddle, and start stirring. The bottom liquid is a mixture of sodium hydroxide, ammonia water and surfactant. The pH value of the bottom liquid is 11.0, the ammonia concentration is 10.0 g / L, and the surfactant concentration is 2 mol / L;

[0093] (11) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) into a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 65° C., the pH to be 11.0, and the ammonia concentration to be 10.0 g / L; and controlling the flow rate of the surfactant to be 1 times the flow rate of the mixed salt solution;

[0094] (12) When the D50 of the material in the reactor is detected to reach 15.0 μm, the feeding is stopped;

[0095] (13) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0096] (14) The solid material is washed and dried, and then sieved and demagnetized in sequence to obtain a ternary precursor with a high tap density.

[0097] A high tap density ternary precursor is prepared by the above preparation method, and its general chemical formula is Ni 0.5 Co 0.2 Mn0.3 (OH)2·xSiO2 is a secondary particle agglomerated by primary particles. The primary particles are blocky cubes with a particle size of 0.1-5.0 μm. The particle size of the agglomerated secondary particles is 15.0 μm.

[0098] Comparative Example 1

[0099] A method for preparing a ternary precursor comprises the following steps:

[0100] (1) According to the element molar ratio of Ni:Co:Mn=6:2:2, nickel sulfate, cobalt sulfate, and manganese sulfate were selected as raw materials to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 1.5 mol / L;

[0101] (2) preparing a sodium hydroxide solution with a concentration of 6.0 mol / L as a precipitant;

[0102] (3) Prepare 8.0 mol / L ammonia water as a complexing agent;

[0103] (4) preparing an aqueous solution of sodium dodecylbenzenesulfonate surfactant with a concentration of 1 mol / L;

[0104] (5) Adding a bottom liquid to the reactor until it covers the bottom stirring paddle, and starting stirring. The bottom liquid is a mixture of sodium hydroxide and ammonia water, the pH value of the bottom liquid is 10.5, and the ammonia concentration is 6.0 g / L;

[0105] (6) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) to a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 55° C., the pH to be 10.5, and the ammonia concentration to be 6 g / L; and controlling the flow rate of the surfactant to be 0.5 times the flow rate of the mixed salt solution;

[0106] (7) When the D50 of the material in the reactor is detected to reach 10.5 μm, the feeding is stopped;

[0107] (8) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0108] (9) The solid material is washed and dried, and then sieved and demagnetized in sequence to obtain the target ternary precursor.

[0109] A ternary precursor is prepared by the above preparation method, and its general chemical formula is Ni 0.6 Co 0.2 Mn 0.2 (OH)2, which is a secondary particle agglomerated by primary particles, and the particle size of the secondary particles is 10.5 μm.

[0110] Comparative Example 2

[0111] A method for preparing a ternary precursor comprises the following steps:

[0112] (1) According to the element molar ratio of Ni:Co:Mn=8:1:1, nickel chloride, cobalt chloride, and manganese chloride were selected as raw materials to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 1.0 mol / L;

[0113] (2) preparing a sodium hydroxide solution with a concentration of 4.0 mol / L as a precipitant;

[0114] (3) Prepare 6.0 mol / L ammonia water as a complexing agent;

[0115] (4) preparing an aqueous solution of sodium dodecylnaphthalenesulfonate surfactant at a concentration of 0.1 mol / L;

[0116] (5) Adding a bottom liquid to the reactor until it covers the bottom stirring paddle, and starting stirring. The bottom liquid is a mixture of sodium hydroxide and ammonia water, with a pH value of 10.0 and an ammonia concentration of 2.0 g / L.

[0117] (6) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) to a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 45° C., the pH to be 10.0, and the ammonia concentration to be 2.0 g / L; and controlling the flow rate of the surfactant to be 0.1 times the flow rate of the mixed salt solution;

[0118] (7) When the D50 of the material in the reactor is detected to reach 5.0 μm, the feeding is stopped;

[0119] (8) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0120] (9) The solid material is washed and dried, and then sieved and demagnetized in sequence to obtain the target ternary precursor.

[0121] A ternary precursor is prepared by the above preparation method, and its general chemical formula is Ni 0.8 Co 0.1 Mn 0.1 (OH)2, which is a secondary particle agglomerated from primary particles, and has a particle size of 5.0 μm.

[0122] Comparative Example 3

[0123] A method for preparing a ternary precursor comprises the following steps:

[0124] (1) nickel nitrate, cobalt nitrate, and manganese nitrate were selected as raw materials according to the element molar ratio of Ni:Co:Mn=5:2:3 to prepare a mixed salt solution with a total nickel, cobalt, and manganese metal ion concentration of 2.5 mol / L;

[0125] (2) preparing a sodium hydroxide solution with a concentration of 8.0 mol / L as a precipitant;

[0126] (3) Prepare ammonia water with a concentration of 12.0 mol / L as a complexing agent;

[0127] (4) preparing a 2 mol / L aqueous solution of sodium lauryl sulfate surfactant;

[0128] (5) Adding a bottom liquid to the reactor until it covers the bottom stirring paddle, and starting stirring. The bottom liquid is a mixture of sodium hydroxide and ammonia water, the pH value of the bottom liquid is 11.0, and the ammonia concentration is 10.0 g / L;

[0129] (6) adding the mixed salt solution prepared in step (1), the sodium hydroxide solution prepared in step (2), the ammonia water prepared in step (3), and the surfactant aqueous solution prepared in step (4) to a reactor in parallel for reaction, controlling the reaction temperature in the reactor to be 65° C., the pH to be 11.0, and the ammonia concentration to be 10.0 g / L; and controlling the flow rate of the surfactant to be 1 times the flow rate of the mixed salt solution;

[0130] (7) When the D50 of the material in the reactor is detected to reach 15.0 μm, the feeding is stopped;

[0131] (8) performing solid-liquid separation on the material in the kettle to obtain a solid material;

[0132] (9) The solid material is washed and dried, and then sieved and demagnetized in sequence to obtain the target ternary precursor.

[0133] A ternary precursor is prepared by the above preparation method, and its general chemical formula is Ni 0.5 Co 0.2 Mn 0.3 (OH)2, which is a secondary particle agglomerated from primary particles, and has a particle size of 15.0 μm.

[0134] Test example:

[0135] The tap densities of the ternary precursors of Examples 1-3 and Comparative Examples 1-3 were measured in accordance with GB / T 5162 Determination of Tap Density of Metal Powders. The measurement results are shown in Table 1.

[0136] Table 1: Tap density measurement results of ternary precursors

[0137] As shown in Table 1, the tap density of the ternary precursor prepared by the preparation method of the present invention is 1.73 g / cm 3 and above, the highest can reach 2.23g / cm 3 At the same time, by comparing Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, it can be seen that when the silica emulsion is not added during the preparation of the ternary precursor, the tap density of the ternary precursor finally prepared is significantly reduced.

[0138] The ternary precursors of Example 1 and Comparative Example 1 were respectively mixed with lithium carbonate at a total molar ratio of lithium element to nickel, cobalt and manganese of 1.08:1, and calcined at 850° C. in an oxygen atmosphere for 12 h to obtain the corresponding positive electrode materials.

[0139] The ternary precursors of Example 2 and Comparative Example 2 were respectively mixed with lithium hydroxide at a total molar ratio of lithium element to nickel, cobalt and manganese of 1.08:1, and calcined at 800° C. in an oxygen atmosphere for 12 h to obtain the corresponding positive electrode materials.

[0140] The ternary precursors of Example 3 and Comparative Example 3 were respectively mixed with lithium carbonate at a total molar ratio of lithium element to nickel, cobalt and manganese of 1.08:1, and calcined at 900° C. in an oxygen atmosphere for 12 h to obtain the corresponding positive electrode materials.

[0141] The cathode material obtained above was assembled into a button-type lithium-ion battery for electrochemical performance testing. The specific steps were as follows: The cathode active material was mixed with acetylene black and PVDF in a mass ratio of 8:1:1 using N-methylpyrrolidone as the solvent. The mixture was then coated onto aluminum foil and dried with forced air at 80°C for 8 hours, followed by vacuum drying at 120°C for 12 hours. The battery was assembled in an argon-protected glove box. The negative electrode was a lithium metal sheet, the separator was a polypropylene film, and the electrolyte was 1M LiPF6-EC / DMC (1:1, v / v). The current density was 1C = 160 mA / g, and the charge and discharge cutoff voltages were 2.7-4.3 V. The test results are shown in Table 2.

[0142] Table 2: Battery electrical performance test results

[0143] As can be seen from Table 2, after the positive electrode material prepared from the ternary precursor prepared by the preparation method of the present invention is assembled into a battery, the 0.1C discharge capacity can reach 173mAh / g and above, and the maximum can reach 208mAh / g; after 100 cycles, the discharge specific capacity can reach 167mAh / g and above, and the maximum can reach 190mAh / g; the cycle retention rate can reach 91.3%, and the maximum can reach 96.5%; at the same time, by comparing Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, and Example 3 and Comparative Example 3, it can be seen that when the silica emulsion is not added during the preparation of the ternary precursor, the performance of the final battery will decrease.

[0144] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing a high tap density ternary precursor, characterized in that: The following steps are involved: (1) adding a silica emulsion to an alkaline base liquid under stirring to form a mixed liquid; (2) adding a mixed salt solution of nickel, cobalt and manganese metal ions, a precipitant, a complexing agent and a surfactant to the mixed solution of step (1) to react so that the D50 of the material in the mixed solution reaches 1.0-3.0 μm; (3) performing solid-liquid separation on the material of step (2) to obtain a solid material, drying the solid material, and then crushing it to obtain a crushed material; (4) mixing the crushed material obtained in step (3) with an alkaline base liquid and a surfactant; (5) adding a mixed salt solution of nickel, cobalt and manganese metal ions, a precipitant, a complexing agent and a surfactant to the mixed solution of step (4) to react so that the D50 of the material in the mixed solution reaches 5.0-15.0 μm; (6) performing solid-liquid separation on the material of step (5) to obtain a solid material, washing and drying the solid material to obtain a ternary precursor with a high tap density.

2. The method for preparing a high tap density ternary precursor according to claim 1, characterized in that: The alkaline base liquid is a mixture of sodium hydroxide and ammonia water, the pH value of the alkaline base liquid is 10.0-11.0, and the ammonia concentration is 2.0-10.0 g / L.

3. The method for preparing a high tap density ternary precursor according to claim 1, wherein: The mass concentration of silicon dioxide in the mixed solution of step (1) is 1-3%, and the particle size of silicon dioxide is 1-100 nm.

4. The method for preparing a high tap density ternary precursor according to claim 1, wherein: The total concentration of nickel, cobalt and manganese metal ions in the nickel, cobalt and manganese metal ion mixed salt solution is 1.0-2.5 mol / L.

5. The method for preparing a high tap density ternary precursor according to claim 1, wherein: The precipitant is a sodium hydroxide solution with a concentration of 4.0-8.0 mol / L.

6. The method for preparing a high tap density ternary precursor according to claim 1, wherein: The complexing agent is ammonia water with a concentration of 6.0-12.0 mol / L.

7. The method for preparing a high tap density ternary precursor according to claim 1, wherein: The surfactant is at least one of an alkylbenzenesulfonate aqueous solution, an alkylnaphthalenesulfonate aqueous solution, and an alkanesulfonate aqueous solution, and the concentration of the surfactant is 0.1-2 mol / L.

8. The method for preparing a high tap density ternary precursor according to claim 1, wherein: The particle size D50 of the crushed material obtained in step (3) is 100-500nm.

9. A high tap density ternary precursor, characterized by: The method is prepared according to any one of claims 1 to 8.

10. The high tap density ternary precursor according to claim 9, characterized in that: The chemical formula of the high tap density ternary precursor is Ni 1-a-b Co a Mn b (OH)2·xSiO2, wherein 0<a<1, 0<b<1, is a secondary particle formed by agglomeration of primary particles. The primary particles are block-shaped cubes, the particle size of the primary particles is 0.1-5.0 μm, and the particle size of the agglomerated secondary particles is 5.0-15.0 μm.