Treatment method of lithium-rich layered positive electrode material and application thereof

Abstract

The application provides a treatment method of a lithium-rich layered positive material, which comprises the following steps: mixing silicate and deionized water in a certain proportion to configure a silicate solution; adding the lithium-rich layered positive material into the silicate solution in a certain proportion, stirring and dispersing to form a suspension; performing spray drying on the suspension to obtain a composite powder; and performing heat treatment on the composite powder to obtain a modified lithium-rich positive material. The treatment method has a simple process flow, and the prepared modified lithium-rich positive material has a stable structure and good physical and electrochemical performances. The application further provides the modified lithium-rich positive material and a lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a method for processing lithium-rich layered cathode materials, modifying lithium-rich cathode materials, and lithium-ion batteries. Background Technology

[0002] Today, the increasing prominence of traditional energy and environmental problems has intensified the demand for new energy sources. Lithium-ion batteries, due to their long lifespan and high energy conversion and storage efficiency, are widely used as ideal power sources for electric vehicles and energy storage devices. However, current lithium-ion batteries have reached a performance bottleneck. With the continuous development of science and technology and the improvement of living standards, their energy density can no longer meet human needs. In lithium-ion batteries, the cathode material is a crucial component and plays a vital role in determining the battery's energy density; therefore, the development and improvement of cathode materials are of paramount importance.

[0003] Lithium-rich layered cathode materials are considered strong contenders for "next-generation cathode materials" due to their advantages in capacity and voltage window. However, their capacity improvement depends on the redox reaction of bulk lattice oxygen, which leads to severe structural changes and gas release during charge and discharge. Furthermore, irreversible side reactions at the interface under high voltage conditions cause significant capacity and voltage degradation during cycling. Therefore, controlling the stability of the lithium-rich material structure and interface is crucial. Existing lithium-rich cathode materials have significant shortcomings and require improvement. Summary of the Invention

[0004] In view of the above, the present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a method for processing lithium-rich layered cathode materials and its application, which obtains modified lithium-rich cathode materials, enhances the structural stability of the materials, thereby improving cycle stability and physical and electrochemical performance. Furthermore, the processing method for lithium-rich layered cathode materials has a simple process flow and is suitable for large-scale industrial production.

[0005] Therefore, in a first aspect, embodiments of the present invention provide a method for processing lithium-rich layered cathode materials, the method comprising the following steps:

[0006] S10. Mix silicate with deionized water in a certain proportion to prepare a silicate solution;

[0007] S20. Add lithium-rich layered cathode material to the silicate solution in a certain proportion, and stir and disperse to form a suspension;

[0008] S30. The suspension is spray-dried to obtain a composite powder;

[0009] S40. The composite powder is heat-treated to obtain a modified lithium-rich cathode material.

[0010] Preferably, the silicate includes at least one of lithium silicate, sodium silicate, and sodium lithium silicate; and / or,

[0011] The concentration of the silicate solution is between 0.5 g / L and 5 g / L; and / or,

[0012] The silicate accounts for 1%-10% of the mass of the lithium-rich layered cathode material.

[0013] Preferably, the lithium-rich layered cathode material is prepared by one of the following methods: molten salt method, sol-gel method, and co-precipitation method; and / or,

[0014] The particle size of the lithium-rich layered cathode material is between 100 nm and 800 nm.

[0015] Preferably, the lithium-rich layered cathode material includes Li a Mn x Ni y Co z O2, Li a Mn x Ni y O2, Li a Mn x Ni y Co z Al w O2, Li a Mn x Ni y Al w At least one of O2, where x+y+z+w=1, 1<a<1.3.

[0016] Preferably, the stirring process takes 1-4 hours; and / or,

[0017] The dispersion is ultrasonic dispersion; preferably, the ultrasonic dispersion time is 30 min to 60 min.

[0018] Preferably, the air intake volume for the spray drying is 200m³. 3 / h-400m 3 The feed rate is 10ml / min-30ml / min, and the spray flow rate is 500L / h-700L / h.

[0019] Preferably, the heat treatment is performed in an air or oxygen atmosphere.

[0020] Preferably, the heating rate of the heat treatment process is 3℃ / min-5℃ / min, the calcination temperature is 400℃-1000℃, and the calcination time is 1h-4h.

[0021] Secondly, embodiments of the present invention also provide a modified lithium-rich cathode material, which is prepared by the processing method described in the first aspect.

[0022] Thirdly, embodiments of the present invention also provide a lithium-ion battery, the lithium-ion battery comprising: a battery cathode made of the modified lithium-rich cathode material described in the second aspect above.

[0023] The modified lithium-rich cathode material prepared by the method of this invention, which is assembled into spheres by spray drying, has a higher porosity than microspheres prepared by the traditional co-precipitation method. This is beneficial for improving the contact effect with the electrolyte and ensuring the capacity of the material.

[0024] The microspheres are connected to each other and to the electrolyte via silicates, which significantly improves the stability of the microsphere structure and the stability at the interface between individual particles, suppresses the escape of irreversible oxygen from the material, and reduces side reactions at the interface.

[0025] High-temperature calcination promotes the diffusion of Si into the material interior, achieving gradient doping of Si near the material surface and inducing the formation of spinel phase. This phase, in conjunction with the protective layer on the particle surface, further enhances the stability of lattice oxygen, inhibits transition metal migration, and reduces capacity and voltage decay.

[0026] Direct batch modification via spray drying is a simple process with high preparation efficiency, high yield, and good electrochemical stability, which is beneficial for industrial production and commercial application. Attached Figure Description

[0027] Figure 1 This is a flowchart of a method for processing lithium-rich layered cathode material according to an embodiment of the present invention;

[0028] Figure 2 This is a scanning electron microscope image of the modified lithium-rich cathode material prepared in Example 1 of the present invention;

[0029] Figure 3 This is a transmission electron microscope (TEM) image of the modified lithium-rich cathode material prepared in Example 1 of the present invention.

[0030] Figure 4 This is a comparison chart of the cycle life of the modified lithium-rich cathode material prepared in Example 1 of the present invention and the lithium-rich layered cathode material prepared in Comparative Example 1 under 1C conditions.

[0031] Figure 5This is a comparison chart of the cycle life of the modified lithium-rich cathode material prepared in Example 2 of the present invention and the lithium-rich layered cathode material prepared in Comparative Example 1 under 0.5C conditions.

[0032] Figure 6 This is a comparison chart of the cycle life of the modified lithium-rich cathode material prepared in Example 3 of the present invention and the lithium-rich layered cathode material prepared in Comparative Example 1 under 1C conditions.

[0033] Figure 7 This is a scanning electron microscope image of the lithium-rich layered cathode material prepared in Comparative Example 1 of the present invention. Detailed Implementation

[0034] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0035] The following disclosure provides numerous different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. Additionally, examples of various specific processes and materials are provided in this invention; however, those skilled in the art will recognize the applicability of other processes and / or the use of other materials.

[0036] Please refer to Figure 1 In a first aspect, embodiments of the present invention provide a method for processing lithium-rich layered cathode materials, the method comprising the following steps:

[0037] S10. Mix silicate with deionized water in a certain proportion to prepare a silicate solution;

[0038] S20. Add lithium-rich layered cathode material to the silicate solution in a certain proportion, and stir and disperse to form a suspension;

[0039] S30. The suspension is spray-dried to obtain a composite powder;

[0040] S40. The composite powder is heat-treated to obtain a modified lithium-rich cathode material.

[0041] Specifically, the silicate includes at least one of lithium silicate, sodium silicate, and sodium lithium silicate.

[0042] Specifically, the concentration of the silicate solution is between 0.5 g / L and 5 g / L.

[0043] The silicate accounts for 1%-10% of the mass of the lithium-rich layered cathode material. Using this mass ratio for mixing and spray drying is beneficial for constructing a surface structure suitable for the capacity utilization of the lithium-rich cathode material.

[0044] Specifically, the lithium-rich layered cathode material is prepared by one of the following methods: molten salt method, sol-gel method, and co-precipitation method.

[0045] The lithium-rich layered cathode material has a particle size of 100nm-800nm. Nanoscale lithium-rich layered cathode materials are beneficial for spray drying to form a regular porous microsphere structure; particles that are too large may result in insufficient particle aggregation during spraying.

[0046] Specifically, the lithium-rich layered cathode material includes Li a Mn x Ni y Co z O2, Li a Mn x Ni y O2, Li a Mn x Ni y Co z Al w O2, Li a Mn x Ni y Al w At least one of O2, where x+y+z+w=1, 1<a<1.3.

[0047] Specifically, the stirring process takes 1-4 hours.

[0048] Specifically, the dispersion is ultrasonic dispersion; preferably, the ultrasonic dispersion time is 30-60 minutes. Performing ultrasonication and stirring within this range allows for better dispersion of the nanoparticles and ensures sufficient contact and uniform mixing with the silicate solution, thereby improving the coating quality.

[0049] Specifically, the air intake volume for the spray drying is 200m³. 3 / h-400m 3 The feed rate is 10 ml / min-30 ml / min, and the spray flow rate is 500 L / h-700 L / h. Spray drying under these conditions yields micron-sized assembled spheres with uniform morphology, high tap density, and complete and uniform coating.

[0050] Specifically, the heat treatment is carried out in an air or oxygen atmosphere.

[0051] Specifically, the heating rate of the heat treatment process is 3℃ / min-5℃ / min, the calcination temperature is 400℃-1000℃, and the calcination time is 1h-4h. Under these conditions, the heat treatment allows for gradient doping of Si on the material surface and introduces a heterogeneous phase that is beneficial to structural stability.

[0052] Secondly, embodiments of the present invention also provide a modified lithium-rich cathode material, which is prepared by the processing method described in the first aspect.

[0053] Thirdly, embodiments of the present invention also provide a lithium-ion battery, the lithium-ion battery comprising: a battery cathode made of the modified lithium-rich cathode material described in the second aspect above.

[0054] The following detailed description, in conjunction with some specific embodiments, further illustrates the specific process and effects of the processing method using the lithium-rich layered cathode material of the present invention, but does not limit the scope of protection of the present invention.

[0055] Example 1

[0056] This embodiment prepares a modified lithium-rich cathode material, specifically including the following steps:

[0057] (1) Preparation of modified lithium-rich cathode materials:

[0058] Weigh 0.02 g of Li₂SiO₃ to prepare a 0.5 g / L solution, then weigh 1 g of Li₂SiO₃ nanolayered lithium-rich material with a particle size of approximately 200 nm prepared by the molten salt method. 1.2 Mn 0.534 Ni 0.133 Co 0.133 O2. Lithium-rich material powder was dispersed in a Li2SiO3 solution, sonicated for 30 min, stirred for 1 h, and then spray-dried. The air intake rate during spraying was 400 m³ / h. 3 The feed rate was 10 ml / min, and the spray flow rate was 500 L / h. The treated sample was placed in an alumina crucible and calcined at 600 °C for 2 hours to obtain Li. 1.2 Mn 0.534 Ni 0.133 Co 0.133 O2@2%Li2SiO3.

[0059] (2) Battery assembly:

[0060] Weigh 0.16g of the modified lithium-rich cathode material prepared in step (1), add 0.02g of super P (conductive carbon black) as a conductive agent and 0.02g of PVDF (polyvinylidene fluoride) as a binder, mix evenly and coat it on aluminum foil to form a cathode sheet. In a vacuum glove box, use a lithium metal sheet as the negative electrode, a polyethylene porous membrane as the separator, and 1mol / L LiPF6 + 2wt% LiBOB in EC:DMC:EMC (volume ratio 1:1:1) as the electrolyte to assemble a CR2023 coin cell.

[0061] Figure 2 The image shows a scanning electron microscope (SEM) image of the modified lithium-rich cathode material prepared in Example 1. As can be seen from the image, the modified lithium-rich cathode material particles have high uniformity, tight interparticle bonding, and stable structure.

[0062] Figure 3 The image shows a perspective scan of the modified lithium-rich cathode material prepared in Example 1. As can be seen from the image, the modified lithium-rich cathode material has a uniform distribution of Si elements, which is beneficial to improving the material performance.

[0063] Figure 4 The graph shows a comparison of the cycle life of the coin cell prepared in Example 1 and the coin cell prepared from the ordinary lithium-rich layered cathode material in Comparative Example 1 under 1C conditions. As can be seen from the graph, the cycle decay of the modified lithium-rich cathode material is significantly less than that of the ordinary lithium-rich layered cathode material.

[0064] Example 2

[0065] This embodiment prepares a lithium-rich layered cathode material, specifically including the following steps:

[0066] (1) Preparation of modified lithium-rich cathode materials:

[0067] Weigh 0.01 g of Na₂SiO₃ to prepare a 0.5 g / L solution, then weigh 1 g of Li₂SiO₃ nanolayered lithium-rich material with a particle size of approximately 200 nm prepared by the sol-gel method. 1.2 Mn 0.534 Ni 0.133 Co 0.133 O2. The lithium-rich material powder was dispersed in a Na2SiO3 solution, sonicated for 30 min, stirred for 1 h, and then spray-dried. The air intake rate during spraying was 400 m³ / h. 3 The feed rate was 10 ml / min, and the spray flow rate was 500 L / h. The treated sample was placed in an alumina crucible and calcined at 600 °C for 2 hours to obtain Li. 1.2 Mn 0.534 Ni 0.133 Co 0.133 O2@1%Na2SiO3.

[0068] (2) Battery assembly:

[0069] Weigh 0.16g of the modified lithium-rich cathode material prepared in step (1), add 0.02g of super P (conductive carbon black) as a conductive agent and 0.02g of PVDF (polyvinylidene fluoride) as a binder, mix evenly and coat it on aluminum foil to form a cathode sheet. In a vacuum glove box, use a lithium metal sheet as the negative electrode, a polyethylene porous membrane as the separator, and 1mol / L LiPF6 + 2% LiBOB in EC:DMC:EMC (volume ratio 1:1:1) as the electrolyte to assemble a CR2023 coin cell.

[0070] Figure 5 The graph shows a comparison of the cycle life of the coin cell prepared in Example 2 and the coin cell prepared from the ordinary lithium-rich layered cathode material in Comparative Example 1 under 0.5C conditions. As can be seen from the graph, the cycle decay of the modified lithium-rich cathode material is significantly less than that of the ordinary lithium-rich layered cathode material.

[0071] Example 3

[0072] This embodiment prepares a modified lithium-rich layered cathode material, specifically including the following steps:

[0073] (1) Preparation of modified lithium-rich cathode materials:

[0074] Weigh 0.02 g of Li₂SiO₃ to prepare a 0.5 g / L solution, then weigh 1 g of Li₂SiO₃ nanolayered lithium-rich material with a particle size of approximately 400 nm prepared by the co-precipitation method. 1.15 Mn 0.56 Ni 0.2 Al 0.04 O2. Lithium-rich material powder was dispersed in a Li2SiO3 solution, sonicated for 30 min, stirred for 1 h, and then spray-dried. The air intake rate during spraying was 400 m³ / h. 3 The feed rate was 10 ml / min, and the spray flow rate was 500 L / h. The treated sample was placed in an alumina crucible and calcined at 600 °C for 2 hours to obtain Li. 1.1 5Mn 0.56 Ni 0.2 Al 0.04 O2@2%Li2SiO3.

[0075] (2) Battery assembly:

[0076] Weigh 0.16g of the modified lithium-rich cathode material prepared in step (1), add 0.02g of super P (conductive carbon black) as a conductive agent and 0.02g of PVDF (polyvinylidene fluoride) as a binder, mix evenly and coat it on aluminum foil to form a cathode sheet. In a vacuum glove box, use a lithium metal sheet as the negative electrode, a polyethylene porous membrane as the separator, and 1mol / L LiPF6 + 2% LiBOB in EC:DMC:EMC (volume ratio 1:1:1) as the electrolyte to assemble a CR2023 coin cell.

[0077] Figure 6 The graph shows a comparison of the cycle life of the coin cell prepared in Example 3 and the coin cell prepared from the ordinary lithium-rich layered cathode material in Comparative Example 1 under 1C conditions. As can be seen from the graph, the cycle decay of the modified lithium-rich cathode material is significantly less than that of the ordinary lithium-rich layered cathode material.

[0078] Comparative Example 1

[0079] Battery assembly:

[0080] Weigh 0.16g of the nano-lithium-rich layered cathode material prepared by the molten salt method, add 0.02g of super P (conductive carbon black) as a conductive agent and 0.02g of PVDF (polyvinylidene fluoride) as a binder, mix evenly and coat it on aluminum foil to form a cathode sheet. In a vacuum glove box, use a lithium metal sheet as the negative electrode, a polyethylene porous membrane as the separator, and 1mol / L LiPF6 + 2% LiBOB in EC:DMC:EMC (volume ratio 1:1:1) as the electrolyte to assemble a CR2023 coin cell.

[0081] Figure 5 The image shows a scanning electron microscope (SEM) image of the lithium-rich layered cathode material used in Comparative Example 1. As can be seen from the image, the conventional lithium-rich layered cathode material has low particle uniformity, loose interparticle bonding, and gaps.

[0082] The comparison graph of the cycle life of the coin cells prepared in Comparative Example 1 under 1C conditions is shown in the figure. Figure 4 As shown, its cycle decay is significantly lower than that of the coin cell prepared from the modified lithium-rich cathode material in Example 1.

[0083] The modified lithium-rich cathode material prepared by the method of this invention, which is assembled into spheres by spray drying, has a higher porosity than microspheres prepared by the traditional co-precipitation method. This is beneficial for improving the contact effect with the electrolyte and ensuring the capacity of the material.

[0084] The microspheres are connected to each other and to the electrolyte via silicates, which significantly improves the stability of the microsphere structure and the stability at the interface between individual particles, suppresses the escape of irreversible oxygen from the material, and reduces side reactions at the interface.

[0085] High-temperature calcination promotes the diffusion of Si into the material interior, achieving gradient doping of Si near the material surface and inducing the formation of spinel phase. This phase, in conjunction with the protective layer on the particle surface, further enhances the stability of lattice oxygen, inhibits transition metal migration, and reduces capacity and voltage decay.

[0086] Direct batch modification via spray drying is a simple process with high preparation efficiency, high yield, and good electrochemical stability, which is beneficial for industrial production and commercial application.

[0087] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0088] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for processing lithium-rich layered cathode material, characterized in that, The processing method includes the following steps: S10. Mix silicate with deionized water in a certain proportion to prepare a silicate solution; S20. Add lithium-rich layered cathode material to the silicate solution in a certain proportion, and stir and disperse to form a suspension; S30. The suspension is spray-dried to obtain a composite powder; S40. The composite powder is heat-treated to obtain a modified lithium-rich cathode material. The modified lithium-rich cathode material includes a lithium-rich particle assembled microsphere structure. The lithium-rich particle assembled microsphere structure has voids inside and the particles inside are connected by silicates. The heat treatment promotes the diffusion of silicon into the material, realizes the gradient doping of silicon near the surface of the material, and induces the generation of spinel phase. The silicate includes at least one of lithium silicate, sodium silicate, and sodium lithium silicate; the silicate accounts for 1%-10% of the mass of the lithium-rich layered cathode material.

2. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, The concentration of the silicate solution is between 0.5 g / L and 5 g / L.

3. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, Lithium-rich layered cathode materials are prepared by one of the following methods: molten salt method, sol-gel method, and co-precipitation method; and / or, The particle size of the lithium-rich layered cathode material is between 100 nm and 800 nm.

4. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, The lithium-rich layered cathode material includes Li a Mn x Ni y Co z O2, Li a Mn x Ni y O2, Li a Mn x Ni y Co z Al w O2, Li a Mn x Ni y Al w At least one of O2, wherein x+y+z+w=1, 1<a<1.

3.

5. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, The stirring process takes 1-4 hours; and / or, The dispersion is ultrasonic dispersion, and the ultrasonic dispersion time is 30 min-60 min.

6. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, The air intake volume for the spray dryer is 200 m³. 3 / h-400m 3 The feed rate is 10ml / min-30ml / min, and the spray flow rate is 500L / h-700L / h.

7. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, The heat treatment is performed in an air or oxygen atmosphere.

8. The method for processing lithium-rich layered cathode material according to claim 1, characterized in that, The heating rate of the heat treatment process is 3℃ / min-5℃ / min, the calcination temperature is 400℃-1000℃, and the calcination time is 1h-4h.

9. A modified lithium-rich cathode material, characterized in that, The lithium-rich layered cathode material is prepared by the processing method described in any one of claims 1-8.

10. A lithium-ion battery, characterized in that, The lithium-ion battery includes a battery cathode made from the modified lithium-rich cathode material as described in claim 9.

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