CN115084466A - Layered ordered @ disordered core-shell structure lithium ion battery cathode material and preparation method and application thereof - Google Patents

Layered ordered @ disordered core-shell structure lithium ion battery cathode material and preparation method and application thereof Download PDF

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CN115084466A
CN115084466A CN202210744453.XA CN202210744453A CN115084466A CN 115084466 A CN115084466 A CN 115084466A CN 202210744453 A CN202210744453 A CN 202210744453A CN 115084466 A CN115084466 A CN 115084466A
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王苏宁
滑纬博
刘来君
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Xian Jiaotong University
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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Abstract

The invention discloses a layered ordered @ disordered core-shell structure lithium ion battery cathode material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion battery cathode materials. The invention adopts a high-temperature molten salt method, and the preparation process comprises the following steps: firstly, a coprecipitation method is adopted to prepare a hydroxide precursor or a carbonate precursor, and then a layered ordered oxide Li (Ni) is prepared by high-temperature calcination x Co y Mn 1‑x‑y )O 2 Then mixing it with proper quantity of molten salt uniformly and calcining at high temp. to extract Li (Ni) with laminated ordered structure x Co y Mn 1‑x‑y )O 2 Lithium/oxygen at the surface to give Li (Ni) x Co y Mn 1‑x‑y )O 2 @Li 1‑m (Ni x Co y Mn 1‑x‑y ) 1+m O 2 A core-shell structure material. The method can prepare the core-shell structure oxide materials with different shell thicknesses in a high-temperature molten salt working section by regulating and controlling the molten salt proportion and the calcining temperature, has excellent circulation stability, and can be effectively applied to the preparation of lithium ion batteries.

Description

Layered ordered @ disordered core-shell structure lithium ion battery cathode material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of preparation of lithium ion cathode materials, and particularly relates to a lithium ion battery cathode material with a layered ordered @ disordered core-shell structure, and a preparation method and application thereof.
Background
Batteries, as an important means of electrical energy storage and conversion, have been the primary means of using electrical energy for many years. Nowadays, batteries on the market mainly include nickel-cadmium batteries, lead-acid batteries, lithium ion batteries, and the like. The lithium ion battery has the advantages of high energy density, no memory effect, small self-discharge effect, long cycle life and the like, and is widely applied to various fields of portable electronic equipment, military equipment, smart power grids, aerospace, electric automobiles and the like. However, with the development of mobile energy storage, application of power batteries and related technical fields, people have made higher demands on energy density, rate capability, endurance, use cost and safety of lithium ion batteries. The lithium ion battery mainly comprises four parts, namely an anode, a cathode, a diaphragm and electrolyte, wherein the specific capacity of an anode material is lower than that of a cathode material, so that the overall performance of the lithium ion battery is limited. Therefore, the method has great value and practical significance for improving the performance of the lithium ion battery anode material.
High nickel layered ternary positive electrode material Li (Ni) x Co y Mn 1-x-y )O 2 (x is not less than 0.6, NCM for short, space group)
Figure BDA0003719086340000011
) Has good application prospect due to the advantages of low price, high capacity, high energy density and the like. Increasing the nickel content can increase the specific capacity of the material. For example, when the nickel content is 0.8, the layered ternary material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) has a specific discharge capacity of about 200mAh g -1 Much higher than other conventional positive electrode materials, e.g. LiCoO 2 (about 150mAh g -1 )、LiFePO 4 (about 160mAh g -1 ) And the like. Therefore, the high nickel ternary material is a necessary trend for the future lithium ion battery material and technology development.
Albeit highThe nickel layered ternary material shows higher specific discharge capacity, but the cycle life is poor, so that the commercial application of the nickel layered ternary material is limited. Mainly due to the unstable structure and surface chemistry of the high nickel material. During the electrochemical cycle process, the high nickel layered structure is easy to generate irreversible structural change, and the electrochemical activity is reduced. On the other hand, residual lithium on the surface of the high-nickel material and CO in the air 2 、H 2 O reacts to easily generate Li 2 CO 3 And LiOH and the like, and increases the interface resistance of the cathode material. Therefore, the improvement of the chemical stability of the structure and the surface is the key for improving the electrochemical cycle performance of the high-nickel layered ternary material. The preparation of the high-nickel layered ternary material at present is generally divided into two working sections: preparing a precursor by a coprecipitation method, and preparing the lithium intercalation oxide by a high-temperature solid phase method. The high-temperature solid-phase reaction needs to be carried out in an oxygen atmosphere to oxidize the divalent nickel in the precursor into trivalent nickel. The surface of the material obtained by the method is unstable in chemical property, and impurities such as lithium hydroxide and lithium carbonate are easily generated, so that the electrochemical performance of the material is seriously influenced.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a lithium ion battery anode material with a layered ordered @ disordered core-shell structure as well as a preparation method and application thereof x Co y Mn 1-x-y )O 2 @Li 1-m (Ni x Co y Mn 1-x-y ) 1+m O 2 Core-shell structure material and has excellent electrochemical performance.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
the invention discloses a preparation method of a layered ordered @ disordered core-shell structure lithium ion battery anode material, which comprises the following steps: preparing hydroxide precursor or carbonate precursor by adopting a coprecipitation method, and then preparing layered ordered oxide Li (Ni) by high-temperature calcination x Co y Mn 1-x-y )O 2 Then, againLayered ordered oxide Li (Ni) x Co y Mn 1-x-y )O 2 Mixing with proper amount of molten salt, high temperature calcining to extract layered ordered Li (Ni) x Co y Mn 1-x-y )O 2 The lithium/oxygen on the surface can be used for preparing the layered ordered @ disordered core-shell structure lithium ion battery anode material Li (Ni) x Co y Mn 1-x-y )O 2 @Li 1-m (Ni x Co y Mn 1-x-y ) 1+m O 2 Wherein m is more than or equal to 0.05 and less than or equal to 0.15, and xm is more than or equal to 0.60 and less than or equal to 1.00; ym is more than or equal to 0.00 and less than or equal to 0.40.
Preferably, the preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material comprises the following steps:
1) preparing solution
According to the formula Li (Ni) x Co y Mn 1-x-y )O 2 The ratio of xm is more than or equal to 0.60 and less than or equal to 1.00; 0.00-ym 0.40, weighing one or more of nickel salt, cobalt salt and manganese salt, adding water, and fully dissolving to obtain the product with the concentration of 0.5-3 mol.L -1 A salt solution;
2) coprecipitation treatment
Water, a precipitator solution, an ammonia water buffer solution and the concentration of 0.5-3 mol.L prepared in the step 1) -1 Mixing the salt solutions to obtain a mixed solution, wherein the pH value of the mixed solution is 8.0-12.0; stirring and reacting for 1-100 h at 40-70 ℃, and filtering, washing and drying the powder obtained by the reaction to obtain a precursor material;
3) high temperature calcination treatment
Uniformly mixing the precursor material and lithium salt, heating to 600-800 ℃ from room temperature in air or oxygen atmosphere, and calcining for 4-20 h to obtain a layered oxide material Li (Ni) x Co y Mn 1-x-y )O 2 ；
4) High temperature molten salt treatment
Mixing Li (Ni) as layered oxide material x Co y Mn 1-x-y )O 2 Mixing with molten salt uniformly, heating to 500-900 ℃ from room temperature in air or oxygen atmosphere, roasting for 2-15 h, washing and drying the roasted powder material, and preparingObtaining the layered ordered @ disordered core-shell structure lithium ion battery anode material Li (Ni) x Co y Mn 1-x-y )O 2 @Li 1-m (Ni x Co y Mn 1-x-y ) 1+m O 2 ，0.05≤m≤0.15。
Preferably, in the step 1), Ni (CH) is adopted as the nickel salt 3 COO) 2 ·4H 2 O、NiSO 4 ·6H 2 O、NiCl 2 ·6H 2 O or Ni (NO) 3 ) 2 ·6H 2 O; the cobalt salt is Co (CH) 3 COO) 2 ·4H 2 O、CoCl 2 ·6H 2 O、CoSO 4 ·7H 2 O or Co (NO) 3 ) 2 ·6H 2 O; manganese salt adopts Mn (CH) 3 COO) 2 ·4H 2 O、MnSO 4 ·H 2 O、MnCl 2 ·4H 2 O or Mn (NO) 3 ) 2 ·4H 2 O。
Preferably, in the step 2), the concentration of the precipitant solution is 2-6 mol.L -1 Is prepared by dissolving sodium hydroxide or sodium carbonate with water; the concentration of the ammonia buffer solution is 1-10 mol.L -1 。
Preferably, in the step 2), the coprecipitation treatment is carried out in a reaction kettle, 1L of deionized water is added into the reaction kettle, and the concentration is respectively 0.5-3 mol.L -1 Adding a salt solution, a precipitator solution and an ammonia buffer solution into a reaction kettle; wherein the liquid inlet speed of the salt solution is controlled to be 0.5-20 mL/min, and the liquid inlet speed of the ammonia buffer solution is controlled to be 0.2-10 mL/min.
Preferably, in the step 2), the stirring reaction speed is controlled to be 200-500 r/min.
Preferably, in the step 3), the molar ratio of the precursor material to the lithium salt is 1: 1.01-1: 1.10; the lithium salt adopts LiOH & H 2 O、LiCH 3 COO、LiNO 3 Or Li 2 CO 3 。
Preferably, in step 4), the layered oxide material Li (Ni) x Co y Mn 1-x-y )O 2 The mass ratio of the molten salt to the molten salt is 1: 1-1: 5; the fused salt adopts Li 2 MoO 4 NaCl, KCl, LiCl and LiNO 3 One or more of them.
The invention also discloses a lithium ion battery anode material with the layered ordered @ disordered core-shell structure, which is prepared by the preparation method, and the first discharge capacity range is 183-228 mAh g under the current density of 2.0-4.3V and 0.1C -1 And after 50 times of circulation, the capacity retention rate is more than 90%.
The invention also discloses an application of the layered ordered @ disordered core-shell structure lithium ion battery cathode material in preparation of a lithium ion battery.
Compared with the prior art, the invention has the following beneficial effects:
the preparation method disclosed by the invention adopts a high-temperature molten salt method, firstly adopts coprecipitation to prepare a precursor material, then mixes lithium and calcines to obtain a high-nickel anode material with a layered ordered structure, then uniformly mixes the high-nickel anode material with a proper amount of molten salt, and extracts Li/O on the surface of a crystal through high-temperature calcination to obtain the layered ordered disordered core-shell structure oxide material. According to the preparation method, the core-shell structure materials with different shell thicknesses can be prepared by adjusting the temperature of a high-temperature molten salt working section and the molten salt proportion. The material prepared by the method has the advantages of uniform particle distribution, controllable particle size and high batch uniformity. The method has the advantages of simple and controllable process flow, easy operation, stable material surface chemistry and crystal structure and contribution to industrial production.
The anode material with the layered ordered @ disordered core-shell structure prepared by the method disclosed by the invention is excellent in electrochemical performance, and the first discharge capacity reaches 183-228 mAh g under the current density of 2.0-4.3V and 0.1C -1 And after 50 times of circulation, the capacity retention rate reaches 91 percent. Therefore, the method can be effectively applied to the preparation of lithium ion batteries.
Drawings
Fig. 1 is a Scanning Electron Microscope (SEM) image of the core-shell structure cathode material prepared in example 1 of the present invention.
Fig. 2 is a High Resolution Transmission Electron Microscope (HRTEM) image of the core-shell structure cathode material prepared in example 1 of the present invention.
Fig. 3 is an X-ray diffraction (XRD) spectrum of the core-shell structure cathode material prepared in example 2 of the present invention.
Fig. 4 is a cycle performance diagram of the core-shell structure cathode material prepared in example 2 of the present invention.
Fig. 5 is an SEM image of the core-shell structure cathode material prepared in example 3 of the present invention.
Fig. 6 is a first charge-discharge curve of the core-shell structure cathode material prepared in example 4 of the present invention.
Fig. 7 is an XRD spectrum of the core-shell structure cathode material prepared in example 5 of the present invention.
Fig. 8 is a first charge-discharge curve of the core-shell structure cathode material prepared in example 5 of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the accompanying drawings:
example 1
In this example, LiNi is represented by the formula 0.9 Mn 0.1 O 2 And (4) batching.
Preparation of LiNi with different shell thicknesses 0.9 Mn 0.1 O 2 @Li 0.95 (Ni 0.9 Mn 0.1 ) 1.05 O 2 The method for preparing the core-shell structure cathode material comprises the following steps:
step 1, solution preparation:
respectively weighing NiSO according to the molar ratio of nickel to manganese of 0.9:0.1 4 ·6H 2 O, and MnSO 4 ·H 2 O, and adding deionized water, stirring and fully dissolving to prepare 3mol L -1 (transition metal) salt solutions of (i); weighing sodium hydroxide solid, adding deionized water, and dissolving to obtain solution with concentration of 6mol L -1 The precipitant solution of (a), i.e., sodium hydroxide solution; taking a proper amount of strong ammonia water, adding deionized water to dilute the strong ammonia water to 10mol L -1 To prepare an ammonia buffer solution.
Step 2, coprecipitation:
before the reaction started, 1L of deionized water was first added to a 5L reactor, followed by introduction of nitrogen to purge the oxygen from the reactor. And respectively injecting the transition metal salt solution and the ammonia buffer solution into the reaction kettle from the feed inlet at feed rates of 0.5ml/min and 0.2ml/min by using a peristaltic pump, and simultaneously regulating the feed rate of the sodium hydroxide solution to control the pH value of the solution in the reaction kettle to be 11.3. The reaction temperature was controlled at 70 ℃ and the stirrer speed was 500 r/min. After the reaction is carried out for 100 hours, the obtained product is filtered, washed and dried to obtain the hydroxide precursor material.
Step 3, calcining:
mixing the hydroxide precursor particles obtained in the step 2 and Li 2 CO 3 Mixing the transition metal salt with the total molar amount of the transition metal salt and the lithium in a ratio of 1:1.1, uniformly mixing the mixture in a ball mill, putting the mixture into a muffle furnace in an oxygen atmosphere, and calcining the mixture at 700 ℃ for 20 hours to obtain the layered LiNi 0.9 Mn 0.1 O 2 。
Step 4. high temperature molten salt
The layered oxide material LiNi obtained in the step 3 0.9 Mn 0.1 O 2 With Li 2 MoO 4 Uniformly mixing the materials according to the mass ratio of 1:2, then placing the materials in a muffle furnace filled with oxygen atmosphere, roasting the materials for 15 hours at 500 ℃, then fully washing the obtained powder with distilled water, and drying the powder to obtain the layered ordered @ disordered core-shell composite high-nickel cathode material.
The layered ordered @ disordered core-shell structure material prepared in the example is in a sphere-like shape, as shown in fig. 1, the secondary particle size is about 10 μm, and an XRD spectrogram shows that the prepared sample has a typical layered structure and a space group is
Figure BDA0003719086340000061
The electron transmission electron microscope of the sample is shown in fig. 2, and it can be seen that the interior of the particle is an ordered layered structure, the surface of the shell layer is a disordered layered structure, and the thickness is about 2 nm.
The process for testing the charge and discharge performance of the cathode material prepared in the example is as follows:
weighing a proper amount of the prepared core-shell structure positive electrode material, acetylene black and polyvinylidene fluoride (PVDF) as a binder according to the mass ratio of 8:1:1, adding the obtained core-shell structure positive electrode material, acetylene black and PVDF as a binder into N-methylpyrrolidone (NMP) to prepare slurry, uniformly coating the slurry on an aluminum foil, and drying the aluminum foil in a vacuum drying oven at the temperature of 80 ℃ for 12 hours. Then, the sheet was cut into a pole piece (12 mm in diameter) using a die. A metal lithium sheet is taken as a negative electrode, a polypropylene film (Celgard 2400) is taken as a diaphragm, LP30 is taken as electrolyte, and the metal lithium sheet, the polypropylene film and the LP30 are assembled into the CR2032 button cell in a glove box filled with argon.
The electrochemical performance test of the battery is carried out under the conditions that the voltage range is 2.0-4.3V and the current density is different, and the result shows that the core-shell structure cathode material LiNi prepared by the embodiment 0.9 Mn 0.1 O 2 @Li 0.95 (Ni 0.9 Mn 0.1 ) 1.05 O 2 O 2 At a current density of 0.1C (1C ═ 200mA g) -1 ) The first charge and discharge capacity under multiplying power is respectively as high as 215mAh g -1 。
Example 2
In this example, LiNi is represented by the formula 0.8 Co 0.1 Mn 0.1 O 2 And (4) batching.
Preparation methodLiNi of different shell thicknesses 0.8 Co 0.1 Mn 0.1 O 2 @Li 0.9 (Ni 0.8 Co 0.1 Mn 0.1 ) 1.1 O 2 The method for preparing the core-shell structure cathode material comprises the following steps:
step 1, solution preparation:
respectively weighing corresponding Ni (CH) according to the molar ratio of nickel, cobalt and manganese elements of 0.8:0.1:0.1 3 COO) 2 ·4H 2 O、Co(CH 3 COO) 2 ·4H 2 O and Mn (CH) 3 COO) 2 ·4H 2 O three salts, and is prepared into 0.5mol L by using ionized water -1 Mixed transition metal salt solution of (a); weighing Na 2 CO 3 And is prepared into 2mol L -1 The precipitant solution of (1); diluting the concentrated ammonia water to 1mol L with deionized water -1 。
Step 2, coprecipitation:
adding 1L deionized water as base solution into 5L reaction kettle, injecting transition metal salt solution and ammonia solution into the reaction kettle from the feed inlet at feed rate of 20ml/min and 10ml/min respectively by peristaltic pump, and regulating Na 2 CO 3 The solution feeding speed is controlled to control the pH value of the solution in the reaction kettle to be 8. The reaction temperature was controlled at 50 ℃ and the stirrer speed at 500 r/min. After reacting for 1h, filtering, washing and drying the product obtained in the reaction kettle to obtain the carbonate precursor material.
Step 3, calcining:
mixing the carbonate precursor particles obtained in the step 2 with LiOH & H 2 O, the total molar amount of the transition metal salt and the ratio of lithium are 1:1.01, the mixture is evenly mixed and then is put into a muffle furnace filled with oxygen atmosphere, and the mixture is calcined for 4 hours at 800 ℃ to obtain the layered LiNi 0.8 Co 0.1 Mn 0.1 O 2 。
Step 4. high temperature molten salt
The layered oxide material LiNi obtained in the step 3 0.8 Co 0.1 Mn 0.1 O 2 Uniformly mixing the mixture with KCl according to the mass ratio of 1:1, then placing the mixture into a muffle furnace for roasting, and roasting for 8 hours at 700 ℃ in an oxygen atmosphere. The obtained powder materialFully washing with distilled water, and drying to obtain the layered ordered @ disordered core-shell composite high-nickel cathode material LiNi 0.8 Co 0.1 Mn 0.1 O 2 @Li 0.9 (Ni 0.8 Co 0.1 Mn 0.1 ) 1.1 O 2 。
The secondary particle size of the layered ordered @ disordered core-shell structure material prepared by the embodiment is about 2 microns, the thickness of the disordered shell layer is about 8nm, and the XRD spectrogram of a sample is shown in figure 3, so that the core-shell material has a three-party layered structure
Figure BDA0003719086340000081
Battery assembly and charge-discharge performance test: the battery assembly and battery charge and discharge test methods were the same as in example 1, and the results showed that LiNi prepared in this example 0.8 Co 0.1 Mn 0.1 O 2 @Li 0.9 (Ni 0.8 Co 0.1 Mn 0.1 ) 1.1 O 2 The first discharge capacity of the positive electrode material at 0.1C is 213mAh g -1 The capacity of the product is still 205mAh g after 30 times of cycle performance -1 。
Example 3
In this example, LiNi is represented by the formula 0.6 Co 0.2 Mn 0.2 O 2 And (4) batching.
Preparation of LiNi with different shell thicknesses 0.6 Co 0.2 Mn 0.2 O 2 @Li 0.85 (Ni 0.6 Co 0.2 Mn 0.2 ) 1.15 O 2 The method for preparing the core-shell structure cathode material comprises the following steps:
step 1, solution preparation:
respectively weighing corresponding Ni (NO) according to the molar ratio of nickel, cobalt and manganese elements of 0.6:0.2:0.2 3 ) 2 ·6H 2 O、Co(NO 3 ) 2 ·6H 2 O and Mn (NO) 3 ) 2 ·4H 2 O three salts and adding deionized water to prepare 2mol L -1 A transition metal salt solution of (a); weighing sodium hydroxide solid, and preparing into 4mol L with deionized water -1 The precipitant solution of (a); use awayDiluting concentrated ammonia water to 5mol L by using ionized water -1 。
Step 2, coprecipitation:
1L of deionized water was added to a 5L reactor, followed by continuous introduction of nitrogen into the reactor to vent the oxygen from the reactor. The transition metal salt solution and the ammonia solution are respectively injected into the reaction kettle from the feed inlet by adopting a peristaltic pump at the feed rates of 1.5ml/min and 2.0ml/min, and the feed rate of the sodium hydroxide solution is regulated and controlled to control the pH value of the solution in the reaction kettle to be 12. The reaction temperature is controlled at 60 ℃, and the rotating speed of the stirrer is 200 r/min. And after reacting for 50 hours, filtering, washing and drying the product obtained in the reaction kettle to obtain the hydroxide precursor material.
Step 3, calcining:
the hydroxide precursor particles obtained in the step 2 and LiCH 3 COO, mixing the total molar amount of transition metal salt and the ratio of lithium is 1:07, uniformly mixing the mixture, placing the mixture in a muffle furnace, and calcining the mixture in air at 800 ℃ for 16 hours to obtain layered LiNi 0.6 Co 0.2 Mn 0.2 O 2 。
Step 4. high temperature molten salt
The layered oxide material LiNi obtained in the step 3 0.6 Co 0.2 Mn 0.2 O 2 Uniformly mixing the powder and NaCl according to the mass ratio of 1:5, then placing the mixture into a muffle furnace for roasting, and roasting the mixture for 2 hours in the air at 900 ℃. Fully washing the obtained powder material with distilled water, and drying to obtain the layered ordered @ disordered core-shell composite high-nickel cathode material LiNi 0.6 Co 0.2 Mn 0.2 O 2 @Li 0.85 (Ni 0.6 Co 0.2 Mn 0.2 ) 1.15 O 2 。
The morphology of the core-shell structure cathode material prepared in this example is shown in fig. 5, and it can be seen from the figure that the particles are in the form of sphere-like agglomerates, and the thickness of the disordered shell layer of the core-shell structure material is 10 nm.
Battery assembly and charge-discharge performance test: the battery assembly and battery charge and discharge test methods were the same as in example 1, and the results showed that LiNi prepared in this example 0.6 Co 0.2 Mn 0.2 O 2 @Li 0.85 (Ni 0.6 Co 0.2 Mn 0.2 ) 1.15 O 2 The first discharge capacity of the cathode material at 0.1C is 183mAh g -1 The capacity retention rate after 50 cycles was 91%.
Example 4
In this example, LiNi is represented by the formula 0.9 Co 0.05 Mn 0.05 O 2 And (4) batching.
Preparation of LiNi with different shell thicknesses 0.9 Co 0.05 Mn 0.05 O 2 @Li 0.92 (Ni 0.9 Co 0.05 Mn 0.05 ) 1.08 O 2 The method for preparing the core-shell structure cathode material comprises the following steps:
step 1, solution preparation:
respectively weighing corresponding NiCl according to the molar ratio of nickel, cobalt and manganese elements of 0.9:0.05:0.05 2 ·6H 2 O、MnCl 2 ·4H 2 O and CoCl 2 ·6H 2 O three salts, and adding deionized water to prepare 1mol L -1 A transition metal salt solution of (a); weighing sodium carbonate solid, adding deionized water, and dissolving completely to obtain a solution with a concentration of 6mol L -1 The precipitant solution of (a); diluting the concentrated ammonia water to 8mol L with deionized water -1 。
Step 2, coprecipitation:
firstly, 1L of deionized water is added into a 5L reaction kettle, a transition metal salt solution and an ammonia solution are respectively injected into the reaction kettle from a feed inlet by a peristaltic pump at the feed speeds of 5.0ml/min and 3.0ml/min, and the feed speed of a sodium carbonate solution is regulated and controlled to control the pH value of the solution in the reaction kettle to be 8.5. The reaction temperature is controlled at 40 ℃, and the rotating speed of the stirrer is 450 r/min. After reacting for 30 hours, filtering, washing and drying the product obtained in the reaction kettle to obtain the carbonate precursor material.
Step 3, calcining:
mixing the carbonate precursor particles obtained in the step 2 with LiNO 3 Mixing the mixture with the total molar weight of the transition metal salt and the ratio of lithium being 1:1.05, uniformly mixing the mixture in a ball mill, then putting the mixture into a muffle furnace, and calcining the mixture in oxygen at 700 ℃ for 12 hours to obtain the layered LiNi 0.9 Co 0.05 Mn 0.05 O 2 。
Step 4. high temperature molten salt
The layered oxide material LiNi obtained in the step 3 0.9 Co 0.05 Mn 0.05 O 2 Uniformly mixing with KCl and NaCl according to the mass ratio of 1:1:1, then placing the mixture into a muffle furnace for roasting, raising the temperature to 680 ℃ in an oxygen atmosphere, and roasting for 15 hours. Fully washing the obtained powder material with distilled water, and drying to obtain the layered ordered @ disordered core-shell composite high-nickel cathode material LiNi 0.9 Co 0.05 Mn 0.05 O 2 @Li 0.92 (Ni 0.9 Co 0.05 Mn 0.05 ) 1.08 O 2 。
The core-shell structure cathode material prepared in the embodiment has a layered structure
Figure BDA0003719086340000101
The appearance is similar to a sphere, the particle size is about 8 mu m, and the thickness of a disordered shell layer is about 6 nm.
Battery assembly and charge-discharge performance test: the battery assembly and battery charge and discharge test methods were the same as in example 1, and the results showed that LiNi prepared in this example 0.9 Co 0.05 Mn 0.05 O 2 @Li 0.92 (Ni 0.9 Co 0.05 Mn 0.05 ) 1.08 O 2 The first discharge capacity of the positive electrode material at 0.1C is 221mAh g -1 As shown in fig. 6.
Example 5
In this example, LiNiO is represented by the formula 2 And (4) batching.
Preparation of LiNiO with different shell thicknesses 2 @Li 0.94 Ni 1.06 O 2 The method for preparing the core-shell structure cathode material comprises the following steps:
step 1, solution preparation:
weighing appropriate amount of Ni (CH) 3 COO) 2 ·4H 2 O, adding deionized water, stirring and fully dissolving to prepare 3mol L -1 A salt solution; weighing sodium hydroxide solid, adding deionized water to prepare into 8mol L -1 The precipitant solution of (a); to get rid ofDiluting concentrated ammonia water to 5mol L by using ionized water -1 。
Step 2, coprecipitation:
firstly, 1L of deionized water is added into a 5L reaction kettle, nitrogen is continuously introduced into the reaction kettle to discharge oxygen in the reaction kettle, a peristaltic pump is adopted to inject a nickel salt solution and an ammonia solution into the reaction kettle from feed inlets at feed speeds of 0.8ml/min and 0.6ml/min respectively, and simultaneously the feed speed of a sodium hydroxide solution is regulated to control the pH value of the solution in the reaction kettle to be 10.8. The reaction temperature was controlled at 50 ℃ and the stirrer speed at 500 r/min. And after the reaction is carried out for 75 hours, filtering, washing and drying the product obtained in the reaction kettle to obtain the hydroxide precursor material.
Step 3, calcining:
mixing the hydroxide precursor particles obtained in the step 2 with LiOH & H 2 O, the total molar amount of the transition metal salt and the ratio of lithium are 1:1.06, the mixture is put into a ball mill to be uniformly mixed, and then the mixture is put into a muffle furnace to be roasted at 600 ℃ for 20 hours to obtain the layered LiNiO 2 。
Step 4. high temperature molten salt
The layered oxide material LiNiO obtained in the step 3 2 Uniformly mixing the mixture with LiCl according to the mass ratio of 1:1, then placing the mixture into a muffle furnace for roasting, and roasting the mixture for 10 hours at 500 ℃ in oxygen. Fully washing the obtained powder material with distilled water, and drying to obtain the layered ordered @ disordered core-shell composite high-nickel cathode material LiNiO 2 @Li 0.94 Ni 1.06 O 2 。
The core-shell structure cathode material prepared in this example is in a sphere-like shape, the particle size is about 12 μm, and an XRD spectrogram is shown in FIG. 7, from which it can be seen that the prepared sample has a layered structure
Figure BDA0003719086340000121
The disordered shell thickness is about 3 nm.
Battery assembly and charge-discharge performance test: the battery assembly and battery charge and discharge test methods were the same as in example 1, and the results showed that LiNiO prepared in this example 2 @Li 0.94 Ni 1.06 O 2 Initial discharge of positive electrode material at 0.1CThe capacitance is 228mAh g -1 As shown in fig. 8.
The method extracts lithium/oxygen on the surface of a layered structure by a high-temperature molten salt method and regulating roasting temperature and molten salt proportion on the basis of lithium-embedded oxide, and can effectively prepare Li (Ni) with different shell thicknesses x Co y Mn 1-x-y )O 2 @Li 1-m (Ni x Co y Mn 1-x-y ) 1+m O 2 Core-shell structure material and has excellent electrochemical performance.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims (10)

1. A preparation method of a lithium ion battery anode material with a layered ordered @ disordered core-shell structure is characterized by comprising the following steps: preparing hydroxide precursor or carbonate precursor by adopting a coprecipitation method, and then preparing layered ordered oxide Li (Ni) by high-temperature calcination x Co y Mn 1-x-y )O 2 Then the layered ordered oxide Li (Ni) x Co y Mn 1-x-y )O 2 Mixing with proper amount of molten salt, high temperature calcining to extract Li (Ni) with ordered laminated structure x Co y Mn 1-x-y )O 2 The lithium/oxygen on the surface can be used for preparing the layered ordered @ disordered core-shell structure lithium ion battery anode material Li (Ni) x Co y Mn 1-x-y )O 2 @Li 1-m (Ni x Co y Mn 1-x-y ) 1+m O 2 Wherein m is more than or equal to 0.05 and less than or equal to 0.15, and x is more than or equal to 0.60 and less than or equal to 1.00; y is more than or equal to 0.00 and less than or equal to 0.40.
2. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material according to claim 1, characterized by comprising the following steps:
1) preparing solution
According to the formula Li (Ni) x Co y Mn 1-x-y )O 2 X is more than or equal to 0.60 and less than or equal to 1.00; y is more than or equal to 0.00 and less than or equal to 0.40, one or more of nickel salt, cobalt salt and manganese salt are weighed, and water is added to fully dissolve the nickel salt, the cobalt salt and the manganese salt to prepare the nickel-manganese-nickel alloy with the concentration of 0.5-3 mol.L -1 A salt solution;
2) coprecipitation treatment
Water, a precipitator solution, an ammonia water buffer solution and the concentration of 0.5-3 mol.L prepared in the step 1) -1 Mixing the salt solutions to obtain a mixed solution, wherein the pH value of the mixed solution is 8.0-12.0; stirring and reacting for 1-100 h at 40-70 ℃, and filtering, washing and drying the powder obtained by the reaction to obtain a precursor material;
3) high temperature calcination treatment
Uniformly mixing the precursor material and lithium salt, heating to 600-800 ℃ from room temperature in air or oxygen atmosphere, and calcining for 4-20 h to obtain a layered oxide material Li (Ni) x Co y Mn 1-x-y )O 2 ；
4) High temperature molten salt treatment
Mixing Li (Ni) as layered oxide material x Co y Mn 1-x-y )O 2 Uniformly mixing with the molten salt, heating to 500-900 ℃ from room temperature in air or oxygen atmosphere, roasting for 2-15 h, washing and drying the roasted powder material to obtain the layered ordered @ disordered core-shell structure lithium ion battery cathode material Li (Ni) x Co y Mn 1-x-y )O 2 @Li 1-m (Ni x Co y Mn 1-x-y ) 1+m O 2 ，0.05≤m≤0.15。
3. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material according to claim 2, characterized in that in the step 1), Ni (CH) is adopted as a nickel salt 3 COO) 2 ·4H 2 O、NiSO 4 ·6H 2 O、NiCl 2 ·6H 2 O or Ni (NO) 3 ) 2 ·6H 2 O; the cobalt salt is Co (CH) 3 COO) 2 ·4H 2 O、CoCl 2 ·6H 2 O、CoSO 4 ·7H 2 O or Co (NO) 3 ) 2 ·6H 2 O; manganese salt adopts Mn (CH) 3 COO) 2 ·4H 2 O、MnSO 4 ·H 2 O、MnCl 2 ·4H 2 O or Mn (NO) 3 ) 2 ·4H 2 O。
4. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material as claimed in claim 2, wherein in the step 2), the concentration of a precipitant solution is 2-6 mol.L -1 Is prepared by dissolving sodium hydroxide or sodium carbonate with water; the concentration of the ammonia buffer solution is 1-10 mol.L -1 。
5. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material as claimed in claim 2, wherein in the step 2), coprecipitation treatment is performed in a reaction kettle, 1L deionized water is added into the reaction kettle, and the concentration is 0.5-3 mol.L -1 Adding a salt solution, a precipitator solution and an ammonia buffer solution into a reaction kettle; wherein the liquid inlet speed of the salt solution is controlled to be 0.5-20 mL/min, and the liquid inlet speed of the ammonia buffer solution is controlled to be 0.2-10 mL/min.
6. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material according to claim 2, characterized in that in the step 2), the stirring reaction speed is controlled to be 200-500 r/min.
7. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material according to claim 2, characterized in that in the step 3), the molar ratio of the precursor material to the lithium salt is 1: 1.01-1: 1.10; the lithium salt adopts LiOH & H 2 O、LiCH 3 COO、LiNO 3 Or Li 2 CO 3 。
8. The preparation method of the layered ordered @ disordered core-shell structure lithium ion battery cathode material according to claim 2, characterized in that, in the step 4), the layered oxide material Li (Ni) is x Co y Mn 1-x-y )O 2 The mass ratio of the molten salt to the molten salt is 1: 1-1: 5; the fused salt adopts Li 2 MoO 4 NaCl, KCl, LiCl and LiNO 3 One or more of them.
9. The layered ordered @ disordered core-shell structure lithium ion battery cathode material prepared by the preparation method of any one of claims 1 to 8 is characterized in that the range of the first discharge capacity under the current density of 2.0 to 4.3V and 0.1C is 183 to 228mAh g -1 And after 50 times of circulation, the capacity retention rate is more than 90%.
10. The use of the layered ordered @ disordered core-shell structure lithium ion battery cathode material of claim 9 in the preparation of a lithium ion battery.
CN202210744453.XA 2022-06-28 2022-06-28 Layered ordered @ disordered core-shell structure lithium ion battery cathode material and preparation method and application thereof Pending CN115084466A (en)

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