A lithium-rich positive electrode material, a preparation method and application thereof

Abstract

The application provides a lithium-rich positive electrode material and a preparation method and application thereof, and relates to the technical field of lithium battery positive electrode materials. 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2.The lithium-rich positive electrode material is prepared by mixing and grinding a nano lithium-rich ternary material and a saccharide substance in a mass ratio of 1:(0.5-4), calcining in an atmosphere with an oxygen content of 20-100% at 450-600 DEG C, and cooling. The saccharide substance forms a layered graphite structure with more defects and is well compounded with the nano lithium-rich ternary material to form a micro-sized structural unit, thereby improving the adhesion of the lithium-rich positive electrode material on the current collector.

Description

Technical Field

[0001] This invention relates to the field of lithium battery cathode material technology, and in particular to a lithium-rich cathode material, its preparation method, and its application. Background Technology

[0002] The impact of load per unit area on cathode materials is mainly reflected in the battery's energy density and charge / discharge performance. Load per unit area refers to the content of active material per unit area of ​​cathode material, which directly affects the battery's energy output and charge / discharge efficiency. Under the premise of ensuring battery safety and stability, increasing the load per unit area can increase the battery's energy density and improve charge / discharge efficiency, thereby enhancing battery performance. However, an excessively low load per unit area may lead to excessively high current density during charge and discharge, increasing the battery's internal resistance and the risk of thermal runaway, thus affecting the battery's safety and stability. Therefore, when selecting cathode materials, it is necessary to comprehensively consider factors such as energy density, safety, cycle life, and cost to set an appropriate load per unit area, while ensuring battery performance.

[0003] Lithium-rich ternary materials are a very promising cathode material for lithium-ion batteries. Currently, most lithium-rich ternary materials are prepared at the nanoscale. Under the existing electrode process conditions, such materials cannot be attached to the current collector with a large load. Improving the load per unit area is a factor that must be considered in the process of commercialization. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium-rich cathode material, its preparation method, and its application.

[0005] In a first aspect, the present invention provides a method for preparing a lithium-rich cathode material, comprising: mixing and grinding a nano-lithium-rich ternary material with a sugar substance at a mass ratio of 1:(0.5-4), calcining the mixture at 450-600°C in an atmosphere with an oxygen content of 20-100%, and then cooling the mixture to obtain the lithium-rich cathode material; wherein the nano-lithium-rich ternary material is a Li-type cathode material with a layered crystal structure. 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2.

[0006] The preparation method provided by this invention improves the uniformity of the two by mixing sugars with nano-lithium-rich ternary materials. In addition, heating and calcining at 450-600℃ can carbonize the sugars, thereby forming a layered graphite structure with many defects, which can be well combined with the nano-lithium-rich ternary materials to form micron-scale structural units, thereby improving the adhesion of the lithium-rich cathode material to the current collector.

[0007] Optionally, the particle size of the nano-lithium-rich ternary material is 50-200 nm.

[0008] Optionally, the carbohydrate includes one of glucose and sucrose.

[0009] Optionally, the nano-lithium-rich ternary material and the sugar are ball-milled and mixed at a speed of 20-600 rpm.

[0010] Optionally, the calcination process at 450-600°C in an atmosphere with an oxygen content of 20-100% includes: heating the mixed and ground solids to 450-600°C at a rate of 5-50°C / min in an atmosphere with an oxygen content of 20-100%.

[0011] Optionally, the atmosphere with an oxygen content of 20-100% includes an air atmosphere.

[0012] Secondly, the present invention provides a lithium-rich cathode material prepared by any of the above-mentioned optional preparation methods, wherein the particle size of the lithium-rich cathode material is 50-200 nm.

[0013] Thirdly, the present invention also provides a lithium-ion battery, including a current collector, wherein the current collector is loaded with a lithium-rich cathode material prepared by any of the above-mentioned optional preparation methods or the lithium-rich cathode material.

[0014] Optionally, the lithium-rich cathode material is loaded onto the current collector at a rate of 20-100 mg / cm³. 2 . Attached Figure Description

[0015] Figure 1 This is a physical image of the electrode sheet prepared by attaching the lithium-rich cathode material to the current collector according to Embodiment 1 of the present invention.

[0016] Figure 2 This is a physical image of the electrode sheet prepared by attaching the lithium-rich cathode material to the current collector according to Embodiment 2 of the present invention.

[0017] Figure 3 This is a physical image of the electrode sheet prepared by attaching the lithium-rich cathode material to the current collector, as provided in Comparative Example 4 of the present invention.

[0018] Figure 4 The charge-discharge performance curve of the button battery made from the lithium-rich cathode material provided in Example 1 of the present invention is shown.

[0019] Figure 5 This is a charge-discharge performance curve of a button battery made from the lithium-rich cathode material provided in Example 2 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0021] This invention provides a method for preparing a lithium-rich cathode material, comprising: mixing and grinding nano-lithium-rich ternary materials and sugars at a mass ratio of 1:(0.5-4), calcining them at 450-600°C in an atmosphere with an oxygen content of 20-100%, and then cooling them to obtain the lithium-rich cathode material.

[0022] In fact, by mixing and grinding the nano-lithium-rich ternary material with sugars, this invention helps to improve the particle size uniformity of the nano-lithium-rich ternary material and sugars, and also promotes their uniform distribution, which is beneficial for the formation of a composite structure in the subsequent calcination process.

[0023] In fact, by mixing the nano-lithium-rich ternary material with sugars at a mass ratio of 1:(0.5-4), this invention can effectively adjust the lithium content in the calcined lithium-rich cathode material, and at the same time, it can effectively ensure the uniform distribution of the nano-lithium-rich ternary material on the layered graphite structure formed after the carbonization of the sugars.

[0024] Specifically, when mixing lithium-rich ternary nanomaterials with carbohydrates, the lithium-rich ternary nanomaterials used are Li-type materials with a layered crystal structure. 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2, in fact, by using this nano-lithium-rich ternary material, can effectively increase the lithium content in the cathode material. At the same time, its layered crystal structure can be well combined and interwoven with the layered graphite structure after carbonization of sugars, thereby forming a stable structural unit.

[0025] In some embodiments, the particle size of the lithium-rich ternary nanomaterial is 50-200 nm. By selecting lithium-rich materials within this particle size range, they can be effectively incorporated into the layered graphite structure formed after the carbonization of carbohydrates, and this also helps the distribution of the formed lithium-rich cathode material on the current collector.

[0026] In some embodiments, when mixing the lithium-rich ternary nanomaterial with a sugar, the sugar used includes either glucose or sucrose. In fact, by selecting economical and readily available glucose or sucrose, the manufacturing cost of the lithium-rich cathode material can be effectively reduced, which is beneficial for large-scale industrial production. Furthermore, the carbonization of glucose and sucrose results in good conductivity, which helps improve the performance and charge / discharge efficiency of the cathode material.

[0027] In fact, when mixing and grinding nano-lithium-rich ternary materials with sugars, ball milling at a speed of 20-600 rpm is beneficial to improve the mixing uniformity and particle size uniformity of nano-lithium-rich ternary materials and sugars. At the same time, ball milling can increase the surface defects of nano-lithium-rich ternary materials, thereby improving the surface activity of nano-lithium-rich ternary materials, which is beneficial for composite in subsequent calcination processes.

[0028] In some embodiments, when ball milling the lithium-rich ternary nanomaterials with carbohydrates, zirconium oxide is used as the milling ball, and the ball-to-material ratio is controlled at (10-20):1. This facilitates thorough mixing of the lithium-rich ternary nanomaterials and carbohydrates. In practice, the preferred milling speed is 50-300 rpm, and more preferably 100-200 rpm.

[0029] In some embodiments, the calcination process at 450-600°C in an atmosphere with an oxygen content of 20-100% includes: heating the mixed and ground solid material to 450-600°C at a rate of 5-50°C / min in an atmosphere with an oxygen content of 20-100%. In practice, continuous heating with the atmosphere temperature helps improve the uniformity of the solid material's temperature rise, preventing the deterioration of the nano-lithium-rich ternary material and sugars within the solid material during drastic temperature changes. Furthermore, calcining the solid material at 450-600°C facilitates the carbonization of the sugars and avoids the reduction of oxygen in the nano-lithium-rich ternary material.

[0030] In some embodiments, the atmosphere with an oxygen content of 20-100% includes an air atmosphere.

[0031] In fact, the present invention also provides a lithium-rich cathode material prepared by any of the above preparation methods, with a particle size of 50-200 nm.

[0032] Meanwhile, this invention also provides a lithium-ion battery, including a current collector, on which a lithium-rich cathode material prepared by any of the above-described preparation methods is loaded. In practice, the loading amount of the lithium-rich cathode material on the current collector is 20-100 mg / cm³. 2 Preferably 20-25 mg / cm³ 2 .

[0033] In fact, the preparation of current collectors loaded with lithium-rich cathode materials includes the following steps:

[0034] S1. Electrode slurry is prepared by mixing lithium-rich cathode material, conductive carbon black and polyvinylidene fluoride in a solvent at a mass ratio of 8:1:1.

[0035] S2. The electrode slurry is coated onto the current collector and dried to obtain a current collector loaded with lithium-rich cathode material.

[0036] Specifically, the solvent used in step S1 is N-methylpyrrolidone. In practice, the solvent used in step S1 can be a commonly used electrode solvent in the art, and its amount is necessary to completely dissolve the lithium-rich cathode material, conductive carbon black, and polyvinylidene fluoride.

[0037] Similarly, when coating the electrode paste onto the current collector in step S2, the coating method can be a common coating method such as roller coating, dip coating, or brush coating, so that the electrode paste can be evenly distributed on the current collector.

[0038] Example 1

[0039] This embodiment 1 provides a method for preparing a lithium-rich cathode material, including the following steps: ... 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2 and glucose were mixed at a mass ratio of 1:0.5 and then milled in a ball mill jar using zirconium oxide as the milling ball at a speed of 100 rpm to obtain a mixture. The mixture was then heated to 500°C in air at a rate of 10°C / min and then cooled to room temperature to obtain a lithium-rich cathode material with an average particle size of 100 nm.

[0040] Example 2

[0041] This embodiment 2 provides a method for preparing a lithium-rich cathode material, including the following steps: [The text abruptly ends here, so the translation stops.] 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2 and glucose were mixed at a mass ratio of 1:4 and then milled in a ball mill jar using zirconium oxide as the milling ball at a speed of 100 rpm to obtain a mixture. The mixture was then heated to 500°C in air at a rate of 10°C / min and then cooled to room temperature to obtain a lithium-rich cathode material with an average particle size of 100 nm.

[0042] Comparative Example 1

[0043] Comparative Example 1 provides a method for preparing a lithium-rich cathode material, including the following steps: [The text abruptly ends here, so the translation stops.] 1.2 Ni 0.13 Co0.13 Mn 0.54 O2 and glucose were mixed at a mass ratio of 1:0.5 and then milled in a ball mill jar using zirconium oxide as the milling ball at a speed of 100 rpm to obtain a mixture. The mixture was then heated to 400°C in air at a rate of 10°C / min and then cooled to room temperature to obtain a lithium-rich cathode material with an average particle size of 100 nm.

[0044] Comparative Example 2

[0045] Comparative Example 2 provides a method for preparing a lithium-rich cathode material, including the following steps: [The text abruptly ends here, so the translation stops.] 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2 and glucose were mixed at a mass ratio of 1:0.5 and then milled in a ball mill jar using zirconium oxide as the milling ball at a speed of 100 rpm to obtain a mixture. The mixture was then heated to 400°C in an argon atmosphere at a rate of 10°C / min and then cooled to room temperature to obtain a lithium-rich cathode material with an average particle size of 100 nm.

[0046] Comparative Example 3

[0047] Comparative Example 3 provides a method for preparing a lithium-rich cathode material, including the following steps: [The text abruptly ends here, so the translation stops.] 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2 and glucose were mixed at a mass ratio of 1:0.5 and then milled in a ball mill jar using zirconium oxide as the milling ball at a speed of 100 rpm to obtain a mixture. The mixture was then heated to 500°C in an argon atmosphere at a rate of 10°C / min and then cooled to room temperature to obtain a lithium-rich cathode material with an average particle size of 100 nm.

[0048] Comparative Example 4

[0049] Comparative Example 4 provides a method for preparing a lithium-rich cathode material, including the following steps: [The text abruptly ends here, so the translation stops.] 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2 and glucose were mixed at a mass ratio of 1:1 and then milled in a ball mill jar using zirconium oxide as the milling ball at a speed of 100 rpm to obtain a mixture. The mixture was then heated to 500°C in an argon atmosphere at a rate of 10°C / min and then cooled to room temperature to obtain a lithium-rich cathode material with an average particle size of 100 nm.

[0050] Performance testing

[0051] The lithium-rich cathode materials prepared in Examples 1 to 2 and Comparative Examples 1 to 4 are loaded onto copper foil to form an electrode sheet, comprising the following steps:

[0052] S1. Electrode slurry is prepared by mixing and dissolving lithium-rich cathode material, conductive carbon black and polyvinylidene fluoride in N-methylpyrrolidone at a mass ratio of 8:1:1.

[0053] S2. After coating the electrode paste onto copper foil and drying it, a loading of 20 mg / cm³ is obtained. 2 Electrode plates.

[0054] In one example, the electrode sheet made using the lithium-rich cathode material prepared in Comparative Example 4 cracked and detached from its surface, such as... Figure 3 As shown, the lithium-rich cathode materials prepared in Examples 1 to 2 and Comparative Examples 1 to 3, when used to make electrode sheets, have smooth surfaces without cracks. A physical image of the electrode sheet made using the lithium-rich cathode material from Example 1 is shown below. Figure 1 As shown, a physical image of the electrode sheet made using the lithium-rich cathode material in Example 2 is shown below. Figure 2 As shown.

[0055] The lithium-rich cathode materials prepared in Examples 1 to 2 and Comparative Examples 1 to 3 were fabricated into electrode sheets, and then packaged with lithium sheets into button batteries. Charge-discharge tests were conducted at a current density of 15 mA / g. The charge-discharge performance of the button batteries corresponding to Examples 1 to 2 are as follows: Figure 4 and Figure 5 The button batteries corresponding to Comparative Examples 1 to 3 showed no electrical performance.

[0056] from Figure 4 and Figure 5 As can be seen from the data, the specific capacities of the button batteries corresponding to Examples 1 and 2 reached 200 mA / g and 190 mA / g, respectively.

[0057] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for preparing a lithium-rich cathode material, characterized in that, include: A lithium-rich ternary nanomaterial was prepared by mixing and grinding a sugar substance at a mass ratio of 1:(0.5-4), followed by calcination at 450-600℃ in an atmosphere with an oxygen content of 20-100% and then cooling. The lithium-rich ternary nanomaterial is a Li-type cathode material with a layered crystal structure. 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2.

2. The preparation method according to claim 1, characterized in that, The particle size of the lithium-rich ternary nanomaterial is 50-200 nm.

3. The preparation method according to claim 1, characterized in that, The sugars include either glucose or sucrose.

4. The preparation method according to claim 1, characterized in that, The nano-lithium-rich ternary material was ball-milled with sugars at a speed of 20-600 rpm.

5. The preparation method according to claim 1, characterized in that, The calcination process at 450-600℃ in an atmosphere with an oxygen content of 20-100% includes: heating the mixed and ground solids to 450-600℃ at a rate of 5-50℃ / min in an atmosphere with an oxygen content of 20-100%.

6. The preparation method according to claim 1, characterized in that, The atmosphere with an oxygen content of 20-100% includes an air atmosphere.

7. A lithium-rich cathode material prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The particle size of the lithium-rich cathode material is 50-200 nm.

8. A lithium-ion battery, characterized in that, It includes a current collector, on which is loaded a lithium-rich cathode material prepared by any one of the preparation methods of claims 1 to 6 or a lithium-rich cathode material as described in claim 7.

9. The lithium-ion battery according to claim 8, characterized in that, The lithium-rich cathode material is loaded at a concentration of 20-100 mg / cm³ on the current collector. 2 .

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