阅读说明：本技术 一种环状孔隙三元正极前驱体及其制备方法 (Annular-pore ternary positive electrode precursor and preparation method thereof ) 是由 倪湖炳 刘刚 牛磊 杨超 王金龙 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种环状孔隙三元正极前驱体及其制备方法,包括以下步骤：(1)配制含有金属离子的混合盐溶液；(2)配制碱金属氢氧化物溶液；(3)配制络合剂溶液；(4)在惰性气体保护下,将步骤(1)所得混合盐溶液和步骤(2)所得碱金属氢氧化物溶液加入反应釜中,并向反应釜中交替通入络合剂,得三元正极前驱体浆料；(5)将所得三元正极前驱体浆料依次经洗涤、干燥、过筛处理。本发明的有益效果为：本发明所述的方法将第一类络合剂和第二类络合剂交替通入使得到的三元正极前驱体的内部孔隙呈环状均匀分布,且前驱体环状孔隙的位置和宽度大小可以通过更改第一类络合剂和第二类络合剂的使用时机进行调控,其改善了正极产品的抗压强度。(The invention discloses a ring-shaped pore ternary positive electrode precursor and a preparation method thereof, wherein the preparation method comprises the following steps: (1) preparing a mixed salt solution containing metal ions; (2) preparing an alkali metal hydroxide solution; (3) preparing a complexing agent solution; (4) under the protection of inert gas, adding the mixed salt solution obtained in the step (1) and the alkali metal hydroxide solution obtained in the step (2) into a reaction kettle, and alternately introducing a complexing agent into the reaction kettle to obtain ternary anode precursor slurry; (5) and washing, drying and screening the obtained ternary positive precursor slurry in sequence. The invention has the beneficial effects that: according to the method, the first type of complexing agent and the second type of complexing agent are alternately introduced to ensure that the internal pores of the obtained ternary anode precursor are uniformly distributed in an annular shape, and the position and the width of the annular pores of the precursor can be regulated and controlled by changing the using time of the first type of complexing agent and the second type of complexing agent, so that the compressive strength of an anode product is improved.)

1. The annular-pore ternary positive electrode precursor is characterized in that the general formula of the annular-pore ternary positive electrode precursor is Ni_xCo_yM_z(OH)_2+aWherein x + y + z is 1, x is more than or equal to 0.5 and less than or equal to 0.95, y is more than or equal to 0 and less than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.5, a is more than or equal to 0 and less than or equal to 0.5, M is a metal element, and M is selected from Mg, Ca and Al, at least one of Ti, Mn, Zr or Zn; annular pores are distributed in the precursor.

2. The method of preparing the cyclic-porosity ternary positive electrode precursor of claim 1, comprising the steps of:

(1) preparing a mixed salt solution containing metal ions; preparing an alkali metal hydroxide solution; preparing a complexing agent solution; the complexing agent solution comprises a first complexing agent and a second complexing agent, wherein the first complexing agent is an ammonia water solution, and the second complexing agent is an amino acid organic complexing agent solution;

(2) under the protection of inert gas, adding the mixed salt solution obtained in the step (1) and an alkali metal hydroxide solution into a reaction kettle, alternately introducing a first complexing agent and a second complexing agent into the reaction kettle, and stirring under a heating condition for reaction to obtain ternary anode precursor slurry;

(3) and (3) washing, drying and screening the ternary anode precursor slurry obtained in the step (2) in sequence to obtain the annular-pore ternary anode precursor.

3. The method for preparing the annular-pore ternary positive electrode precursor according to claim 2, wherein in the step (1), the total concentration of the metal ions in the mixed salt solution is 1-3 mol/L.

4. The method according to claim 2, wherein in the step (1), the alkali metal hydroxide solution is at least one of a NaOH solution, a KOH solution, or a LiOH solution.

5. The method according to claim 2, wherein the concentration of the alkali metal hydroxide solution in step (1) is 1 to 15 mol/L.

6. The method for preparing the cyclic-pore ternary positive electrode precursor according to claim 2, wherein in the step (2), the amino acid organic complexing agent solution is an aqueous solution of at least one of glycine, methionine or tryptophan.

7. The method for preparing the annular-pore ternary positive electrode precursor according to claim 2, wherein the concentration of the ammonia water solution is 5-10mol/L, and the concentration of the amino acid organic complexing agent solution is 0.01-20 g/L.

8. The method for preparing the annular-pore ternary cathode precursor according to claim 2, wherein in the step (2), the inert gas is nitrogen with the purity of more than or equal to 99.85%, the heating reaction temperature is 40-80 ℃, the pH value of a reaction system in a reaction kettle is 10-13, and the ammonia value is 1-20 g/L.

9. The method for preparing the cyclic-porosity ternary positive electrode precursor according to claim 2, wherein in the step (2), the flowing-in time of the first type of complexing agent is T1, and the flowing-in time of the second type of complexing agent is T2, wherein T1 and T2 satisfy the relation: t2 is more than or equal to 2 and less than or equal to 300 is more than or equal to T1-2.

10. The method for preparing the cyclic-porosity ternary positive electrode precursor according to claim 2, wherein in the step (3),

the temperature of the washing water is 50-80 ℃; the washing equipment is at least one of a filter press, a centrifuge and a washing and drying integrated machine;

the drying temperature is 80-250 ℃; the drying equipment is an oven, a tray dryer, a rotary kiln, a flash evaporation machine or a spray dryer.

Technical Field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a ring-shaped pore ternary positive electrode precursor and a preparation method thereof.

Background

With the development of the society and the progress of science and technology, the technical development of the lithium ion battery is more and more mature, and the nickel cobalt lithium manganate ternary positive electrode material used by the lithium ion battery has the advantages of high capacity, long service life, low cost and the like.

The ternary precursor is the key for synthesizing the ternary battery anode material, directly influences the performance of the battery material, and has the problems that the internal part of the precursor is too compact, so that the high-nickel ternary anode material has low compressive strength and is easy to crack, the cycle performance is poor, and the service life of the battery is shortened.

Patent application publication No. CN 109485104 a discloses a method for reducing the crystallinity of a ternary material precursor by increasing the specific surface area (BET) of the ternary precursor through a micro bubble device, which physically purges an oxidizing gas to the liquid phase portion of a reaction solution, oxidizes cobalt elements and additive elements, increases the specific surface area (BET) of the precursor, and simultaneously reduces the crystallinity. However, this method requires the addition of special equipment for increasing the oxidizing gas, only the porosity can be directionally increased, and the blowing of air by physical means cannot ensure the uniform distribution of the gas inside the solution.

Disclosure of Invention

The application mainly aims to provide a ternary positive electrode precursor with high compressive strength and a preparation method thereof.

In order to achieve the above purpose, the invention provides the following technical scheme:

the annular pore ternary positive electrode precursor has a general formula of Ni_xCo_yM_z(OH)_2+aWherein x + y + z is 1, x is more than or equal to 0.5 and less than or equal to 0.95, y is more than or equal to 0 and less than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.5, a is more than or equal to 0 and less than or equal to 0.5, M is a metal element, and M is selected from at least one of Mg, Ca, Al, Ti, Mn, Zr or Zn; annular pores are distributed in the precursor.

The second aspect of the application provides a preparation method of a ring-shaped pore ternary positive electrode precursor, which comprises the following steps:

(1) preparing a mixed salt solution containing metal ions; preparing an alkali metal hydroxide solution; preparing a complexing agent solution; the complexing agent solution comprises a first complexing agent and a second complexing agent, wherein the first complexing agent is an ammonia water solution, and the second complexing agent is an amino acid organic complexing agent solution;

(2) under the protection of inert gas, adding the mixed salt solution obtained in the step (1) and an alkali metal hydroxide solution into a reaction kettle, alternately introducing a first complexing agent and a second complexing agent into the reaction kettle, and stirring under a heating condition for reaction to obtain ternary anode precursor slurry;

(3) and (3) washing, drying and screening the ternary anode precursor slurry obtained in the step (2) in sequence to obtain the annular-pore ternary anode precursor.

According to the preparation method of the annular pore ternary cathode precursor, the difference of the complexing ability of the ammonia water and the amino acid complexing agent on the nickel-cobalt-manganese salt is utilized (primary particles formed by the amino acid complexing agent are slender and loose in accumulation, and can form a plurality of pore structures), the internal porosity distribution of the precursor is controlled, and the problems that the compression strength of a cathode product is low, and the structural damage and poor circulation are caused by crystal extrusion in the use process of a battery are solved.

As a preferred embodiment, the total concentration of metal ions in the mixed salt solution is 1-3 mol/L.

In the above method for preparing the annular-pore ternary cathode precursor, as a preferred embodiment, in the step (1), the alkali metal hydroxide solution is at least one of NaOH, KOH or LiOH.

Preferably, in the step (1), the concentration of the alkali metal hydroxide solution is 1 to 15 mol/L.

In the above method for preparing the cyclic pore ternary cathode precursor, as a preferred embodiment, in the step (2), the amino acid organic complexing agent solution is an aqueous solution of at least one of glycine, methionine or tryptophan.

Preferably, the concentration of the ammonia water solution is 5-10mol/L, and the concentration of the amino acid organic complexing agent solution is 0.01-20 g/L.

As a preferred embodiment, in the step (2), the inert gas is nitrogen with the purity of more than or equal to 99.85%, the heating reaction temperature is 40-80 ℃, the pH value of a reaction system in a reaction kettle is 10-13, and the ammonia value is 1-20 g/L.

As a preferred embodiment, in step (2), the introduction time of the first type of complexing agent is T1, and the introduction time of the second type of complexing agent is T2, where T1 and T2 satisfy the following relation: t2 is more than or equal to 2 and less than or equal to 300 is more than or equal to T1-2.

In the precursor growth process, the width of the internal pores of the precursor can be controlled by controlling the introduction time of the amino acid complexing agent, and the longer the introduction time is, the wider the pores are. The number of passes is equal to the number of possible ring structures.

In the preparation method of the annular pore ternary positive electrode precursor, as a preferred embodiment, in the step (3), the temperature of washing water is 50-80 ℃; the washing equipment is at least one of a filter press, a centrifuge and a washing and drying integrated machine;

the drying temperature is 80-250 ℃; the drying equipment is an oven, a tray dryer, a rotary kiln, a flash evaporation machine or a spray dryer.

The invention has the beneficial effects that: the annular pore ternary positive electrode precursor is a spherical structure material formed by stacking metal hydroxide primary particles. Primary particles formed by the amino acid complexing agent are slender and loose in accumulation, and a porous structure can be formed; the primary particles formed by the ammonia water are thicker, and the inner part is relatively tightly stacked. The first type of complexing agent and the second type of complexing agent are alternately introduced to ensure that the internal pores of the obtained ternary anode precursor are uniformly distributed in an annular shape, and the position and the width of the annular pores of the precursor can be regulated and controlled by changing the use time of the first type of complexing agent and the second type of complexing agent, so that the compressive strength of the anode product is improved.

In addition, the annular-pore ternary positive electrode precursor can be prepared by adopting the existing reaction kettle, only one feeding hole is needed to be added on the reaction kettle, and the operation is convenient.

Drawings

FIG. 1 is an SEM image of a cyclic pore ternary positive electrode precursor obtained in example 1 of the present invention;

FIG. 2 is an SEM image of a cyclic pore ternary positive electrode precursor obtained in example 2 of the present invention;

FIG. 3 is an SEM image of a cyclic pore ternary positive electrode precursor obtained in comparative example 1 of the present invention;

fig. 4 is an SEM image of the cyclic pore ternary positive electrode precursor obtained in comparative example 2 of the present invention.

Detailed Description

In order to make the technical solutions in the embodiments of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to examples, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The invention describes a ring-shaped pore ternary positive electrode precursor, wherein the general formula of the ring-shaped pore ternary positive electrode precursor is Ni_xCo_yM_z(OH)_2+aWherein x + y + z is 1, x is more than or equal to 0.5 and less than or equal to 0.95, y is more than or equal to 0 and less than or equal to 0.3, z is more than or equal to 0 and less than or equal to 0.5, a is more than or equal to 0 and less than or equal to 0.5, M is a metal element, and M is selected from at least one of Mg, Ca, Al, Ti, Mn, Zr or Zn; annular pores are distributed in the precursor.

Example 1

In the embodiment 1, an annular pore with a width of about 2um is formed in the annular pore ternary positive electrode precursor.

The preparation method of the annular-pore ternary cathode precursor in the embodiment 1 comprises the following steps:

preparing a nickel-cobalt-manganese sulfate solution with the total metal ion concentration of 1.5mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 80:10: 10; preparing a sodium hydroxide solution with the concentration of 5 mol/L; respectively preparing ammonia water with the concentration of 10mol/L and glycine solution with the concentration of 5 g/L;

introducing a certain amount of nitrogen with the purity of more than or equal to 99.85% into a reaction kettle for protection, adding the nickel-cobalt-manganese sulfate solution and the sodium hydroxide solution into the reaction kettle, introducing ammonia water with the concentration of 10mol/L under the conditions that the reaction temperature is 60 ℃ and the PH is 10.8, reacting for T1 being 80 hours, and when the granularity is 6um, closing the ammonia water, and switching the complexing agent to the glycine solution; when the reaction time T2 was 40 hours and the particle size was 8um, the glycine solution was turned off and ammonia was switched again. And (3) after the granularity reaches 11 mu m and the reaction is finished, carrying out solid-liquid separation on the slurry, washing with washing water with the water temperature of 50 ℃ (wherein the washing equipment can be a filter press, a centrifuge and a washing and drying integrated machine), drying at the temperature of 80 ℃ (wherein the drying equipment can be an oven, a tray dryer, a rotary kiln, a flash evaporation machine or a spray dryer), and sieving to obtain the product. The SEM image of the ternary cathode precursor with annular pores obtained in example 1 is shown in fig. 1, and it can be seen from fig. 1 that the inside of the obtained product has an annular pore with a width of about 2 um.

Example 2

Embodiment 2 the inside of the ring-shaped pore ternary positive electrode precursor is provided with two ring-shaped pores with the width of about 2 um.

The preparation method of the annular-pore ternary cathode precursor in the embodiment 2 comprises the following steps:

preparing a nickel-cobalt-manganese sulfate solution with the total metal ion concentration of 1.5mol/L, wherein the ratio of nickel ions to cobalt ions to manganese ions is 80:10: 10; preparing a sodium hydroxide solution with the concentration of 5 mol/L; respectively preparing ammonia water with the concentration of 10mol/L and glycine solution with the concentration of 5 g/L;

introducing a certain amount of nitrogen with the purity of more than or equal to 99.85% into a reaction kettle for protection, adding the nickel-cobalt-manganese sulfate solution and the sodium hydroxide solution into the reaction kettle, introducing ammonia water with the concentration of 10mol/L under the conditions that the reaction temperature is 60 ℃ and the PH is 10.8, closing the ammonia water when the granularity reaches 10um, switching the complexing agent to be glycine solution, reacting for 2h at T2, switching the complexing agent to be glycine complexing agent once every 4h, washing with washing water with the temperature of 65 ℃ (wherein the available washing equipment is a filter press, a centrifuge and a washing and drying integrated machine), drying at 160 ℃ (wherein the available drying equipment is an oven, a tray dryer, a rotary kiln, a flash evaporation machine or a spray dryer), and sieving to obtain a product. The SEM image of the cyclic pore ternary cathode precursor obtained in example 2 is shown in fig. 2, and it can be seen from fig. 2 that two cyclic pores with a width of about 2um are formed in the obtained product. In the preparation method of embodiment 2, in the time process of preparing the total ternary positive electrode precursor, the second type of complexing agent (glycine solution complexing agent) can be introduced twice according to the alternation time of the first type of complexing agent and the second type of complexing agent, so that two annular pores with the width of about 2um in the shape of a strip are formed.

Example 3

The preparation method of the annular-pore ternary cathode precursor in the embodiment 3 comprises the following steps:

preparing a nickel-cobalt-manganese sulfate solution with the total metal ion concentration of 1mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 80:10: 10; preparing a potassium hydroxide solution with the concentration of 1 mol/L; respectively preparing 5mol/L ammonia water and 0.05g/L glycine solution;

introducing a certain amount of nitrogen with the purity of more than or equal to 99.85% into a reaction kettle for protection, adding the nickel-cobalt-manganese sulfate solution and the potassium hydroxide solution into the reaction kettle, introducing ammonia water with the concentration of 5mol/L under the conditions that the reaction temperature is 40 ℃ and the PH is 10, reacting for T1 being 80 hours and the granularity being 6um, closing the ammonia water, and switching the complexing agent to a glycine solution; when the reaction time T2 was 40 hours and the particle size was 8um, the glycine solution was turned off and ammonia was switched again. And (3) after the reaction is finished, performing solid-liquid separation on the slurry, washing with washing water with the water temperature of 50 ℃ (wherein the washing equipment can be a filter press, a centrifugal machine and a washing and drying integrated machine), drying at the temperature of 80 ℃ (wherein the drying equipment can be an oven, a disc dryer, a rotary kiln, a flash evaporation machine or a spray dryer), and sieving to obtain a product, wherein the inside of the obtained product is provided with an annular hole with the width of about 2 microns.

Example 4

The preparation method of the cyclic-pore ternary cathode precursor in the embodiment 4 comprises the following steps:

preparing a nickel-cobalt-manganese sulfate solution with the total metal ion concentration of 3mol/L, wherein the molar ratio of nickel ions to cobalt ions to manganese ions is 80:10: 10; preparing a lithium hydroxide solution with the concentration of 15 mol/L; respectively preparing ammonia water with the concentration of 10mol/L and glycine solution with the concentration of 20 g/L;

introducing a certain amount of nitrogen with the purity of more than or equal to 99.85% into a reaction kettle for protection, adding the nickel-cobalt-manganese sulfate solution and the sodium hydroxide solution into the reaction kettle, introducing ammonia water with the concentration of 10mol/L under the conditions that the reaction temperature is 60 ℃ and the PH is 10.8, reacting for T1 being 80 hours, and when the granularity is 6um, closing the ammonia water, and switching the complexing agent to the glycine solution; when the reaction time T2 was 40 hours and the particle size was 8um, the glycine solution was turned off and ammonia was switched again. And (3) after the reaction is finished, performing solid-liquid separation on the slurry, washing with washing water with the water temperature of 80 ℃ (wherein the washing equipment can be a filter press, a centrifuge and a washing and drying integrated machine), drying at 250 ℃ (wherein the drying equipment can be an oven, a disc dryer, a rotary kiln, a flash evaporation machine or a spray dryer), and sieving to obtain a product, wherein the inside of the obtained product is provided with an annular hole with the width of about 2 microns.

Example 5

In example 5, an annular aperture with a width of about 2um is formed in the annular aperture ternary positive electrode precursor.

Example 5 differs from example 1 in that: the second type of complexing agent used in example 5 was tryptophan.

Example 6

In example 6, an annular aperture with a width of about 2um is formed in the annular aperture ternary positive electrode precursor.

Example 6 differs from example 1 in that: the second type of complexing agent used in example 6 was methionine.

Example 7

In example 7, the inside of the ring-shaped pore ternary cathode precursor has a ring-shaped pore with a width of about 2 um.

Example 7 differs from example 1 in that: the second class of complexing agents used in example 7 was a mixture of methionine and tryptophan.

Comparative example 1

The method for preparing the ternary positive electrode precursor described in comparative example 1 is different from the method for preparing the cyclic pore ternary positive electrode precursor described in example 1 in that: only the complexing agent ammonia water is introduced into the ternary positive electrode precursor in the preparation process of the comparative example 1.

The scan of the ternary positive electrode precursor obtained in comparative example 1 is shown in fig. 3: as can be seen from fig. 3, the ternary positive electrode precursor is relatively dense in the interior, and has only individual pores, and does not form a ring structure. The SEM image of the cyclic pore ternary positive electrode precursor obtained in comparative example 1 is shown in fig. 3.

Comparative example 2

The method for preparing the ternary positive electrode precursor described in comparative example 2 is different from the method for preparing the cyclic pore ternary positive electrode precursor described in example 2 in that: and (3) only introducing a glycine complexing agent into the ternary cathode precursor in the preparation process of the comparative example 2.

The scan of the ternary positive electrode precursor obtained in comparative example 2 is shown in fig. 4: as can be seen from fig. 4, the internal pores of the ternary positive electrode precursor are uniformly distributed throughout, and do not form a ring structure. The SEM image of the cyclic pore ternary positive electrode precursor obtained in comparative example 2 is shown in fig. 4.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.