阅读说明：本技术 一种补锂剂及其制备方法和应用 (Lithium supplement agent and preparation method and application thereof ) 是由 陈思贤 江卫军 郑晓醒 许鑫培 于 2021-09-30 设计创作，主要内容包括：本发明属于锂离子电池技术领域,具体涉及一种补锂剂及其制备方法和应用。本发明利用分段煅烧方式,首先将氢氧化锂利用较低温度下将氢氧化锂分解为氧化锂,同时在分解过程中氧化锂可以与镍源进行结合,然后将材料置于高温环境中继续进行煅烧,从而获得所需材料。其优点在于降低了对于混料设备的要求,不需要进行气氛保护,并且利用分段煅烧工艺,能够有效地提升材料的颗粒粒径,有效降低材料的活性,利于材料能够在空气中更为稳定的存在。同时较长的反应时间降低材料表面的残碱。对材料进行充放电测试表明,材料具有较高的充电容量,较低的放电容量,表明材料本身接纳锂离子能力较差,能够有效地为正极材料提供锂离子,适合作为补锂添加剂。(The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium supplement agent and a preparation method and application thereof. According to the invention, a sectional calcination mode is utilized, lithium hydroxide is firstly decomposed into lithium oxide at a lower temperature, meanwhile, the lithium oxide can be combined with a nickel source in the decomposition process, and then the material is placed in a high-temperature environment for continuous calcination, so that the required material is obtained. The method has the advantages that the requirement on mixing equipment is reduced, atmosphere protection is not needed, and the particle size of the material can be effectively improved by using a segmented calcination process, so that the activity of the material is effectively reduced, and the material can stably exist in the air. Meanwhile, the longer reaction time reduces the residual alkali on the surface of the material. The charge and discharge tests of the material show that the material has higher charge capacity and lower discharge capacity, which indicates that the material has poorer lithium ion accepting capability, can effectively provide lithium ions for the anode material, and is suitable for serving as a lithium supplement additive.)

1. The preparation method of the lithium supplement agent is characterized by comprising the following steps:

mixing a lithium source and a nickel source, calcining at 600 ℃ for 3-8h in the presence of protective gas, heating to 600 ℃ and 800 ℃ for 7-12h, and cooling to obtain the lithium supplement agent.

2. The method for preparing a lithium supplement agent according to claim 1, wherein the temperature rise rate during the calcination is 2-4 ℃/min.

3. The method for preparing a lithium supplementing agent according to claim 1, wherein the molar ratio of the lithium source to the nickel source is 2.0 to 2.5 in terms of lithium element and nickel element.

4. The method for preparing a lithium supplementing agent according to any one of claims 1 to 3, wherein the lithium source is lithium hydroxide.

5. The method for preparing a lithium supplementing agent according to any one of claims 1 to 3, wherein the nickel source is at least one of nickel oxide, nickel protoxide and nickel hydroxide.

6. The method for preparing the lithium supplement agent according to claim 1, wherein the flow rate of the protective gas is 2-10L/min.

7. The method for preparing a lithium supplementing agent according to claim 6, wherein the protective gas is nitrogen or an inert gas.

8. A lithium supplementing agent prepared by the preparation method of any one of claims 1 to 7.

9. The lithium supplement agent according to claim 8, wherein the particle size of the lithium supplement agent is 500nm-1 μm, and the surface residual alkali is 10000ppm-30000 ppm.

10. The lithium supplement agent prepared by the preparation method of any one of claims 1 to 7 or the lithium supplement agent of any one of claims 8 to 9 is applied as a lithium supplement agent of a lithium ion battery cathode material.

Technical Field

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium supplement agent and a preparation method and application thereof.

Background

With the increasing prominence of the problems of energy environmental pollution and the like, the development and the utilization of new energy are imperative. In the coming years, the application demand of lithium ion batteries in the new energy automobile industry will be continuously increased. In new energy automobiles, lithium ion batteries occupy a core position, and in the lithium ion batteries, positive electrode materials are important.

In the charge and discharge process of the lithium ion battery, especially in the first cycle charge and discharge process, due to the formation of the SEI film, partial lithium in the material is confined in the negative electrode, so that the material has the problems of low first effect, low capacity and the like. In view of these problems, lithium replenishers have come into play. Because of the active nature of metallic lithium, lithium-rich compounds are often used as a source of lithium ions.

Li₂NiO₂As a new lithium supplement agent, the lithium ion battery has great effect on improving the capacity of battery materials, and only a small amount of Li₂NiO₂The electrochemical performance of the material can be greatly improved by using the method. However, the lithium supplement agent finished product material prepared by the conventional method has the problems of high activity, small particle size, poor crystallinity, difficulty in stably existing in an air environment, high first effect of the material, and the like, which indicates that the lithium ion is extracted from the material in the charging process, and the lithium ion is inserted back in the discharging process, so that the lithium ion cannot be effectively provided. In addition, the positive electrode material is supplemented with Li₂NiO₂Most of the raw materials for the preparation are Li₂O, and Li₂O is very easy to react with moisture in the air and carbon dioxide to generate lithium hydroxide and lithium carbonate, so that the atmosphere needs to be controlled in the material mixing process, and the material mixing difficulty is increased.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to overcome the defects that the lithium supplement agent in the prior art is unstable and cannot effectively provide lithium ions, and the like, so that the lithium supplement agent, the preparation method and the application thereof are provided.

Therefore, the invention provides the following technical scheme:

the invention provides a preparation method of a lithium supplement agent, which comprises the following steps:

mixing a lithium source and a nickel source, calcining at 600 ℃ for 3-8h in the presence of protective gas, heating to 600 ℃ and 800 ℃ for 7-12h, and cooling to obtain the lithium supplement agent. For example, the calcination temperature in the first stage may be 300 ℃, 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃; the calcination time of the first stage is 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h and 8 h; the calcination temperature in the second stage may be 600 ℃, 630 ℃, 650 ℃, 680 ℃, 700 ℃, 720 ℃, 750 ℃, 780 ℃, 800 ℃.

Optionally, the heating rate in the calcining process is 2-4 ℃/min. For example, the temperature rise rate can be 2 ℃/min, 2.3 ℃/min, 2.5 ℃/min, 2.8 ℃/min, 3 ℃/min, 3.2 ℃/min, 3.5 ℃/min, 3.8 ℃/min, 4 ℃/min.

Optionally, the molar ratio of the lithium source to the nickel source is 2.0-2.5 calculated by lithium element and nickel element. For example, the molar ratio of the lithium source to the nickel source is 2.0, 2.1, 2.2, 2.3, 2.4, 2.5.

Optionally, the lithium source is lithium hydroxide.

Optionally, the nickel source is at least one of nickel oxide, nickel protoxide and nickel hydroxide.

Optionally, the flow rate of the protective gas is 2-10L/min. For example, the flow rate of the shielding gas is 2L/min, 2.2L/min, 2.5L/min, 2.8L/min, 3L/min, 3.3L/min, 3.5L/min, 3.8L/min, 4L/min, 5L/min, 5.5L/min, 6L/min, 6.5L/min, 7L/min, 7.5L/min, 8L/min, 8.5L/min, 9L/min, 9.5L/min, 10L/min.

Optionally, the protective gas is nitrogen or inert gas.

The invention also provides a lithium supplement agent prepared by the preparation method.

Optionally, the particle size of the lithium supplement agent is 500nm-1 μm, and the surface residual alkali is 10000-30000 ppm.

The invention also provides a lithium supplement prepared by the preparation method or an application of the lithium supplement as a lithium supplement for a lithium ion battery anode material.

According to the preparation method of the lithium supplement agent, lithium hydroxide and a nickel-containing compound are used as raw materials, and the raw materials are calcined in an inert atmosphere, so that the positive electrode material with high initial charge capacity is obtained. The calcining process is mainly divided into two parts, wherein the first part is to calcine the mixed material of lithium hydroxide and a nickel-containing compound at low temperature under an inert condition, so as to promote the decomposition of the lithium hydroxide into lithium oxide and ensure that part of the lithium oxide can react with the nickel-containing compound to obtain a relatively stable intermediate product; the second part is mainly to promote the lithium oxide to further react with the nickel-containing compound by utilizing a high-temperature inert gas environment, and finally obtain the required product. The grain diameter of the primary particles of the obtained material is in a nanometer level, and part of the nanometer level primary particles are agglomerated to form micron level secondary particles. By utilizing the two-step calcining process, the particle size of the material can be effectively improved, and the stability of the material can be effectively improved by using larger primary particles, so that the material can exist in the air more stably. Meanwhile, the nickel salt and the lithium salt can be more fully reacted by longer reaction time, the residual alkali on the surface of the material can be effectively reduced, and the subsequent links of homogenate coating and the like can be favorably implemented. Meanwhile, the charge and discharge tests of the material show that the material has higher charge capacity, which shows that the material can effectively provide a large amount of lithium ions in the first charge and discharge process; meanwhile, the material has low discharge capacity, which shows that the material has poor lithium ion accepting capability, can effectively provide lithium ions for the anode material, and only consumes a small amount of lithium ions.

The technical scheme of the invention has the following advantages:

1. the preparation method of the lithium supplement agent provided by the invention comprises the following steps: mixing a lithium source and a nickel source, calcining at 600 ℃ for 3-8h in the presence of protective gas, heating to 600 ℃ and 800 ℃ for 7-12h, and cooling to obtain the lithium supplement agent. By utilizing a sectional calcining mode, firstly, the lithium hydroxide is decomposed into lithium oxide at a lower temperature, meanwhile, the lithium oxide can be combined with a nickel source in the decomposition process, and then the material is placed in a high-temperature environment for continuous calcining, so that the required material is obtained. The method has the advantages that the requirement on mixing equipment is reduced, atmosphere protection is not needed, the materials are decomposed and recombined by using the inert environment in the calcining process, and the particle size of the materials can be effectively improved by using the sectional calcining process, so that the activity of the materials is effectively reduced, and the materials can stably exist in the air. Meanwhile, the nickel salt and the lithium salt can be more fully reacted by longer reaction time, the residual alkali on the surface of the material can be effectively reduced, and the subsequent links of homogenate coating and the like can be favorably implemented. The charge and discharge tests of the material show that the material has higher charge capacity, and the material has lower discharge capacity, which shows that the material has poorer lithium ion accepting capability, and shows that the material can effectively provide lithium ions for the anode material and is suitable for being used as a lithium supplement additive.

According to the preparation method of the lithium supplement agent provided by the invention, parameters such as the heating rate, the raw material ratio and the atmosphere are limited, so that the particle size of the obtained material can be further controlled, the valence state of nickel element is ensured, and the obtained material is controlled to form a compound with a stoichiometric ratio.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a charge-discharge curve of lithium replenisher provided in examples of the present invention and comparative examples.

Detailed Description

The following examples are provided to further understand the present invention, not to limit the scope of the present invention, but to provide the best mode, not to limit the content and the protection scope of the present invention, and any product similar or similar to the present invention, which is obtained by combining the present invention with other prior art features, falls within the protection scope of the present invention.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.

Example 1

The embodiment provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.0;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 300 ℃ at the heating rate of 4 ℃/min, preserving heat for 8h, then heating to 600 ℃ at the heating rate of 2 ℃/min, and preserving heat for 12 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Example 2

The embodiment provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.5;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 600 ℃ at the heating rate of 2 ℃/min, preserving heat for 3h, then heating to 800 ℃ at the heating rate of 4 ℃/min, and preserving heat for 7 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Example 3

The embodiment provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (nickel hydroxide) according to a molar ratio of Li/Ni elements of 2.1;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 500 ℃ at the heating rate of 3 ℃/min, preserving heat for 5h, then heating to 700 ℃ at the heating rate of 3 ℃/min, and preserving heat for 10 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Example 4

The embodiment provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.4;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 500 ℃ at the heating rate of 4 ℃/min, preserving heat for 6h, then heating to 750 ℃ at the heating rate of 3 ℃/min, and preserving heat for 9 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Example 5

The embodiment provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni element of 2.2;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 450 ℃ at the heating rate of 3 ℃/min, preserving heat for 5h, then heating to 750 ℃ at the heating rate of 3 ℃/min, and preserving heat for 12 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Example 6

The embodiment provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, lithium hydroxide and a nickel-containing compound (N)i(OH)₂) Evenly mixing according to the molar ratio of Li to Ni element of 2.2;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 450 ℃ at the heating rate of 3 ℃/min, preserving heat for 5h, then heating to 700 ℃ at the heating rate of 3 ℃/min, and preserving heat for 10 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Comparative example 1

The comparative example provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.0;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 300 ℃ at the heating rate of 4 ℃/min, and keeping the temperature for 20h, wherein the protective gas in the calcining process is argon, and the flow is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Comparative example 2

The comparative example provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.0;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 600 ℃ at the heating rate of 4 ℃/min, and keeping the temperature for 20h, wherein the protective gas in the calcining process is argon, and the flow is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Comparative example 3

The comparative example provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.0;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 280 ℃ at the heating rate of 4 ℃/min, preserving heat for 10h, then heating to 850 ℃ at the heating rate of 2 ℃/min, and preserving heat for 5 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Comparative example 4

The comparative example provides a lithium supplement agent, and the specific preparation method comprises the following steps:

(1) under a dry environment, uniformly mixing lithium hydroxide and a nickel-containing compound (NiO) according to the molar ratio of Li to Ni elements of 2.0;

(2) and (3) placing the uniformly mixed material in a box-type furnace for calcination, wherein the calcination operation comprises the following steps: heating to 650 ℃ at the heating rate of 4 ℃/min, preserving heat for 2h, then heating to 600 ℃ at the heating rate of 2 ℃/min, and preserving heat for 5 h; the protective gas in the calcining process is argon, and the flow rate is 10L/min;

(3) and naturally cooling the calcined sample to obtain the lithium supplement material.

Examples of the experiments

The lithium supplement material obtained in the embodiment and the comparative example of the invention is subjected to performance tests, including particle size, surface residual alkali, ICP and charge and discharge performance tests, and the specific test method and test results are as follows:

1. performing particle size characterization by using a laser diffraction method (laser particle sizer);

2. carrying out surface residual alkali test by adopting an electrochemical titration method; the method comprises the following specific steps: 10g of the lithium supplement material prepared in each example and comparative example was weighed, dispersed in 100ml of water, and after sufficient stirring and filtration, 50ml of supernatant was taken, hydrochloric acid was used as a titrant, and after the acid-base titration was performed to the end point, the contents of lithium hydroxide and lithium carbonate (surface residual base amount) were determined from the amount of hydrochloric acid used and the inflection point of the titration.

3. The lithium supplement agent materials obtained in the embodiments and the comparative examples are subjected to charge and discharge tests, and the specific steps are as follows: 1. and (3) homogenate coating: positive electrode material (lithium supplement material prepared in example or comparative example): binder (polyvinylidene fluoride): conductive agent (conductive carbon black) 92: 4: and 4, placing the mixture in a defoaming machine, uniformly mixing, and then performing electric fastening assembly. 2. And (4) buckling and assembling: the buckling assembly was performed in the order of positive electrode case (304 stainless steel), spring plate (304 stainless steel), gasket (304 stainless steel), positive electrode (aluminum foil coated with positive electrode material), separator (PE), electrolyte (1mol/L LiPF6, solvent EC (ethylene carbonate): DEC (diethyl carbonate) in a volume ratio of 3:7), negative electrode (lithium plate), and negative electrode case (304 stainless steel). 3. -a power-off test: and standing the assembled battery for 12 hours at the constant temperature of 25 ℃ to enable the electrolyte to fully soak the electrode material. Then the test voltage is 2.0-4.8V when the test is carried out on a LAND CT-2001A test system. FIG. 1 is a charge-discharge curve of lithium replenisher provided in examples of the present invention and comparative examples.

TABLE 1

The data in the table show that when the calcination temperature is low, the particle size of the material is small, the residual alkali is high, and the lithium nickel ratio is low, which may be that the calcination temperature is low, the material reaction is incomplete, which results in high residual alkali and low specific discharge capacity.

By adopting the preparation method, on one hand, lithium hydroxide is decomposed to generate lithium oxide, the mixing is reduced, the control on the calcining atmosphere in the preparation process of the material is controlled, the crystallinity of the material is ensured in the subsequent inert gas calcining process, and simultaneously, the lithium hydroxide can be melted, so that the uniformity of the material mixing is better facilitated. The longer reaction time can enable the nickel salt and the lithium salt to react more fully, can effectively reduce the residual alkali on the surface of the material, and is beneficial to the implementation of subsequent links such as homogenate coating and the like. Meanwhile, the charge and discharge tests of the material show that the material has higher charge capacity, which shows that the material can effectively provide a large amount of lithium ions in the first charge and discharge process; meanwhile, the material has low discharge capacity, which shows that the material has poor lithium ion accepting capability, can effectively provide lithium ions for the anode material, and only consumes a small amount of lithium ions.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.