Method for manufacturing composite positive electrode material

Abstract

To provide a preparation method of composite cathode material, materializing a simple and quick preparation process and enabling effective improvement of cathode material.SOLUTION: A preparation method of a composite cathode material includes steps of (a) providing a nickel-manganese compound material, wherein the nickel-manganese compound material is NixMny(OH)2 or NixMnyO(x+y=1); (b) of providing a solid electrolyte material, and forming a composite material by mixing the nickel-manganese compound material with the solid electrolyte material by a mechanical mixing method, wherein a weight percent of the solid electrolyte material relative to the nickel-manganese compound material is 0.2 wt.% to 1.0 wt.%; and (c) of providing a Li source, mixing the Li source with the composite material, forming the composite cathode material by sintering them, wherein the composite cathode material comprises a core layer and a coated layer, the core layer is made of LiNi2xMn2yO4, and the coated layer is made of the solid electrolyte material.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a cathode material for secondary batteries, and more particularly to a method for preparing a composite cathode material, in which a precursor and a solid electrolyte are treated by dry mechanical mixing to form a cathode material, while simultaneously completing the surface coating of the solid electrolyte. This method is simple and fast to prepare, and can effectively improve the performance of the cathode material. [Background technology]

[0002] In recent years, the performance requirements for electric vehicles (e.g., electric vehicles) and their energy storage devices have been increasing, and high performance is also required for the secondary batteries used in them. Among the many types of batteries, lithium manganese nickel oxide / spinel (LiMn 1.5 Ni 0.5 O4,LMNO) is known as a cathode material that can be charged at a high voltage (5 V). The high potential allows lithium manganese nickel oxide / spinel materials to have a higher energy density compared to lithium cobalt oxide and lithium iron phosphate, making LMNO-based batteries widely usable for high-energy and high-rate applications.

[0003] However, the capacity of LMNO is affected by electrolyte decomposition at high voltages, which can easily lead to problems such as reduced capacitance, rate capability, and cycle life. Therefore, surface modification of LMNO has become an important challenge. Furthermore, conventional methods for combining LMNO with solid electrolytes typically involve coating the LMNO material with a solid electrolyte to improve the microstructure of the LMNO surface. This results in the formation of a skeletal surface that can impart ionic conductivity and electrical conductivity to the LMNO surface, effectively alleviating the poor cycle performance at high voltages and improving the conductive properties of LMNO. However, conventional LMNO coating on solid electrolytes requires complicated procedures, and the coating of the solid electrolyte may impair the performance of LMNO.

[0004] In view of the above, the present invention provides a method for manufacturing a composite positive electrode material to solve the problems encountered in the prior art. Specifically, the precursor and the solid electrolyte are processed by dry mechanical mixing to form the positive electrode material, and the surface coating of the solid electrolyte is completed at the same time. This makes the manufacturing process simple and fast, and effectively improves the performance of the positive electrode material. Summary of the Invention [Problem to be solved by the invention]

[0005] The objective of the present invention is to provide a method for manufacturing a composite cathode material. Specifically, a dry mechanical fusion method is used to process a precursor and a solid electrolyte to form a cathode material, while simultaneously completing the surface coating of the solid electrolyte. This makes the manufacturing process simple and fast, and can effectively improve the performance of the cathode material. The cathode material, lithium nickel manganese oxide (LMNO), is mixed with lithium aluminum titanium phosphate (Li 1.3 Al 0.3 Ti 1.7 In coating the (PO4)3,LATP) solid electrolyte, the present invention uses a dry mechanical mixing method to coat Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 The nickel manganese compound material and the solid electrolyte material are mixed first, then a lithium source is added and mixed, followed by sintering to form a composite cathode material with a core layer and a coating layer. The inner core layer is LiNi 0.5 Mn 1.5O4, and the outer coating layer is made of a solid electrolyte material. Lithium aluminum titanium phosphate (LATP) solid electrolyte has inherently excellent ion conductivity properties, so when it coats the surface of the lithium nickel manganese oxide cathode material LMNO to form a composite cathode material, it helps improve the rate performance and cycle performance of the lithium nickel manganese oxide cathode material LMNO. The lithium aluminum titanium phosphate (LATP) coating layer also provides a protective function that delays the damage caused by the electrolyte to the material surface. Furthermore, to achieve the optimal solid electrolyte coating effect, Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 The weight percentage of the solid electrolyte material relative to the nickel manganese compound material such as O is controlled to 0.2 wt.% to 1.0 wt.%, preferably 0.2 wt.% to 0.3 wt.%. That is, in the present invention, by simply adding a small amount of lithium aluminum titanium phosphate LATP solid electrolyte, it is possible to form a coating layer that improves the rate performance of the lithium nickel manganese oxide positive electrode material LMNO, and further reduce the production cost.

[0006] Another object of the present invention is to provide a method for preparing a composite cathode material. Rather than directly coating lithium aluminum titanium phosphate (LATP) on the lithium nickel manganese oxide cathode material LMNO, the present invention uses a mechanical method, for example, mechanofusion method, to mix lithium aluminum titanium phosphate (LATP) into the pre-processing material of the lithium nickel manganese oxide cathode material LMNO to form the lithium nickel manganese oxide cathode material LMNO, thereby allowing the Mn 3+ The production of Mn is further reduced. 3+This prevents the dissolution of lithium from the positive electrode material, its reduction and deposition on the negative electrode, and its subsequent electrical degradation during cycling. The mixing process is typically performed at temperatures between 25°C and 45°C, with rotation speeds between 700 rpm and 3500 rpm, for 5 to 30 minutes in stages. By controlling the mixing method, operating temperature, rotation speed, and time of the lithium aluminum titanium phosphate (LATP) and pretreatment material, structural defects in the solid electrolyte coating layer caused by high temperatures or excessive friction between particles can be prevented. At the same time, the lithium nickel manganese oxide positive electrode material LMNO exhibits low impedance and good charge / discharge performance due to the LATP solid electrolyte coating. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a nickel manganese compound material, which comprises: Ni x Mn y (OH)2 or Ni x Mn y and x+y=1; step (a) of providing a solid electrolyte material, and mixing the nickel manganese compound material and the solid electrolyte material by mechanical mixing to form a composite material, the weight percentage of the solid electrolyte material to the nickel manganese compound material being 0.2 wt.%-1.0 wt.%; step (b) of providing a lithium source, and mixing the lithium source and the composite material and sintering to form the composite positive electrode material, the composite positive electrode material having a core layer and a coating layer, the core layer being LiNi 2x Mn 2y and step (c) comprising a coating layer covering the core layer, the coating layer comprising the solid electrolyte material. Preferably, the nickel manganese compound material is Ni 0.25 Mn 0.75(OH)2, and in step (b), after mechanical mixing, a first heat treatment process is carried out, the temperature range of the first heat treatment process is 300°C to 850°C, the treatment time of the first heat treatment process is 5 hours to 7 hours, and the temperature rising rate of the first heat treatment process is 2.5°C / min. Preferably, the nickel manganese compound material is Ni 0.25 Mn 0.75 O, and step (a) includes a pre-oxidation process, the temperature range of the pre-oxidation process is 300°C to 850°C, the treatment time of the pre-oxidation process is 5 hours to 7 hours, and the temperature rising rate of the pre-oxidation process is 2.5°C / min. Preferably, in step (b), after mechanical mixing, a first heat treatment process is carried out, the temperature range of the first heat treatment process is 300°C to 750°C, the treatment time of the first heat treatment process is 5 hours to 7 hours, and the temperature rising rate of the first heat treatment process is 2.5°C / min. Preferably, in step (b), the process of mechanically mixing the nickel manganese compound material and the solid electrolyte includes mixing at a rotation speed of 700 rpm for 5 minutes, mixing at a rotation speed of 1400 rpm for 5 minutes, mixing at a rotation speed of 2100 rpm for 5 minutes, mixing at a rotation speed of 2800 rpm for 10 minutes, and mixing at a rotation speed of 3500 rpm for 10 minutes. Preferably, in step (b), the operating temperature for mechanically mixing the nickel manganese compound material and the solid electrolyte is 25°C to 45°C. Preferably, the chemical formula of the solid electrolyte is Li 1+z Al z Ti 2-z (PO4)3, where z≦2. Preferably, the mechanical method includes mechanical fusion. Preferably, in step (c), the process of mechanically mixing the lithium source and the composite material includes mixing at a rotation speed of 700 rpm for 5 minutes and then mixing at a rotation speed of 1400 rpm for 30 minutes. Preferably, step (c) includes a second heat treatment process, the temperature range of the second heat treatment process is 300°C to 710°C, the treatment time of the second heat treatment process is 24 hours to 30 hours, and the temperature rising rate of the second heat treatment process is 2.5°C / min. Preferably, in step (c), the molar ratio of the nickel manganese compound material to the lithium source in the composite material is 1:1.02. Preferably, the weight percentage is between 0.2 wt.% and 0.3 wt.%. Preferably, the nickel manganese compound material has an average particle size of 10 μm to 20 μm, and the solid electrolyte material has an average particle size of 1 μm to 5 μm. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual structural diagram of a positive electrode material according to an embodiment of the present invention. [Figure 2A] 1 is an SEM image of the Ni0.25Mn0.75(OH)2 nickel manganese compound material of the present invention. [Figure 2B] 1 is an SEM image of a nickel manganese compound material of Ni0.25Mn0.75O of ​​the present invention. [Figure 2C] 1 is an SEM image of lithium aluminum titanium phosphate (LATP) of the present invention. [Figure 3] 1 is a flowchart of a method for producing a composite positive electrode material according to a first embodiment of the present invention. [Figure 4] In FIG. 4, 4A to 4D are SEM images of the positive electrode material of the first comparative example. [Figure 5] In FIG. 5, 5A to 5D are SEM images of the positive electrode material of the first example of the present invention. [Figure 6] In FIG. 6, 6A to 6D are SEM images of the positive electrode material of the second example of the present invention. [Figure 7] In FIG. 7, 7A to 7D are SEM images of the positive electrode material of the third example of the present invention. [Figure 8]FIG. 10 is a diagram showing potential-capacity charge-discharge curves of the first comparative example, the first example, the second example, and the third example of the present invention. [Figure 9] FIG. 10 is a graph showing the capacity retention rate vs. cycle number discharge curves for the first comparative example, the first example, the second example, and the third example of the present invention. [Figure 10] 4 is a flowchart of a method for producing a composite positive electrode material according to a second embodiment of the present invention. [Figure 11] In FIG. 11, 11A to 11D are SEM images of the positive electrode material of the fourth example of the present invention. [Figure 12] In FIG. 12, 12A to 12D are SEM images of the positive electrode material of the fifth example of the present invention. [Figure 13] In FIG. 13, 13A to 13D are SEM images of the positive electrode material of the sixth example of the present invention. [Figure 14] FIG. 10 is a diagram showing potential-capacity charge-discharge curves of the first comparative example, the fourth example, the fifth example, and the sixth example of the present invention. [Figure 15] FIG. 10 is a graph showing the capacity retention rate vs. cycle number discharge curves for the first comparative example, the fourth, fifth, and sixth examples of the present invention. [Figure 16] FIG. 10 is a diagram showing potential-capacity charge-discharge curves for the second comparative example, the third comparative example, the first example of the present invention, and the fourth example. [Figure 17] FIG. 10 is a graph showing the capacity retention rate vs. cycle number discharge curves for the third comparative example, the first example of the present invention, and the fourth example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Several exemplary embodiments embodying the features and advantages of the present invention are described in detail below. The present invention is susceptible to various modifications without departing from its scope. The following description and drawings are used to explain the present invention, not to limit it. Furthermore, in the detailed description of the present invention, the term "arranged on or above a second feature" refers to an embodiment in which the first and second features are directly connected, and an embodiment in which the first and second features are not directly connected via another structure between them. Furthermore, terms such as "first," "second," and "third" are used to describe different configurations described in the claims, but these configurations are not limited to these terms. In the context of the embodiments, although the corresponding configurations are represented by different reference numerals, the first configuration may be represented as the second configuration, and the second configuration may be represented as the first configuration, without departing from the scope of the present invention. Furthermore, the term "and / or" means one or more related elements or all combinations thereof. The term "approximately" refers to a mean value within a standard error range generally accepted by those skilled in the art. Unless expressly defined in the operational / operating embodiments, all numerical ranges, amounts, values, percentages, etc. (e.g., angles, maintenance times, temperatures, operating conditions, ratios, and equivalent percentages) described herein should be understood in all embodiments as being "about" or "substantially." Furthermore, unless otherwise stated in the context, all numerical values ​​in the present invention and claims can be approximated, which can vary as necessary. For example, each parameter can be construed in light of at least the stated number of significant digits and by applying ordinary rounding rules. Furthermore, numerical ranges herein can be expressed as a range from one endpoint to the other endpoint or between two endpoints. It should be noted that all ranges described herein include the endpoints unless otherwise defined.

[0010] 1 is a conceptual structural diagram of a composite positive electrode material according to an embodiment of the present invention. In this embodiment, the composite positive electrode material 1 includes a core layer 10 and a coating layer 20 that covers the core layer 10. The core layer 10 is made of a lithium nickel manganese oxide positive electrode material LMNO, and the composition of the lithium nickel manganese oxide positive electrode material LMNO is LiNi 0.5 Mn 1.5 The coating layer 20 is made of lithium aluminum titanium phosphate (Li 1.3 Al 0.3 Ti 1.7 In this embodiment, the lithium nickel manganese oxide cathode material LMNO is a cobalt-free high-voltage cathode material with a relatively high redox potential and energy density. The composite cathode material 1 can be used in a liquid electrolyte 30, and the lithium manganese oxide cathode material LMNO is a cobalt-free high-voltage cathode material with a relatively high redox potential and energy density. + Ions 11 can pass through the coating layer 20 formed of a solid electrolyte and undergo intercalation or deintercalation into the lithium nickel manganese oxide positive electrode material LMNO in the inner core layer 10. The composite positive electrode material 1 of the present invention is formed by mixing lithium aluminum titanium phosphate (LATP) into a pretreatment material for the lithium nickel manganese oxide positive electrode material LMNO by a mechanical method such as mechanofusion method to form the lithium nickel manganese oxide positive electrode material LMNO. The pretreatment material can be, for example, Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 The nickel manganese compound material of O, and the lithium nickel manganese oxide positive electrode material LMNO are not directly used in the coating process. 0.25 Mn 0.75 FIG. 2B is an SEM image of the Ni(OH)2 nickel manganese compound material of the present invention. 0.25 Mn 0.75FIG. 2C is an SEM image of a nickel-manganese compound material. FIG. 2C is an SEM image of lithium aluminum titanium phosphate (LATP) of the present invention. Of course, the types, composition ratios, and material properties of the core layer 10 and the coating layer 20 covering the core layer 10 used in the composite positive electrode material 1 of the present invention can be adjusted according to the requirements of the actual application and are not limited thereto. A method for manufacturing the composite positive electrode material 1 of the present invention, in which a precursor and a solid electrolyte are treated by a dry mechanical fusion method, will now be described.

[0011] 3 is a flowchart of a method for manufacturing a composite positive electrode material according to a first embodiment of the present invention. In this embodiment, a nickel manganese compound material is first provided, wherein the nickel manganese compound material is Ni 0.25 Mn 0.75 (OH)2 (Step S01). 0.25 Mn 0.75 The average particle size of the (OH)2 nickel manganese compound material is 10 μm to 20 μm, for example, 12.90 μm, and the surface area is 0.6 m 2 / g. Next, a lithium aluminum titanium phosphate (LATP) solid electrolyte material is provided, and the average particle size of the solid electrolyte material is 1 μm to 5 μm, for example, 1.79 μm. 0.25 Mn 0.75 The (OH)2 nickel manganese compound material and the LATP solid electrolyte material are mechanically mixed to form a composite material (step S02). 0.25 Mn 0.75The weight percentage of the LATP solid electrolyte material relative to the (OH)2 nickel manganese compound material is 0.2 wt.% to 1.0 wt.%. In this embodiment, the mechanical method refers to a dry mechanofusion method. In step S02, mixing the nickel manganese compound material and the solid electrolyte by a mechanical method includes mixing at a rotation speed of 700 rpm for 5 minutes, mixing at a rotation speed of 1400 rpm for 5 minutes, mixing at a rotation speed of 2100 rpm for 5 minutes, mixing at a rotation speed of 2800 rpm for 10 minutes, and mixing at a rotation speed of 3500 rpm for 10 minutes. The operating temperature for mixing the nickel manganese compound material and the solid electrolyte by a mechanical method is 25°C to 45°C. After the mechanical mixing, a first heat treatment process is performed (step S03). The first heat treatment temperature is 300°C to 850°C, the treatment time of the first heat treatment step is 5 hours to 7 hours, and the temperature rising rate in the first heat treatment step is 2.5°C / min.

[0012] Next, as shown in step S04, a lithium source, such as lithium hydroxide, is provided (prepared), and the lithium source and the composite material are mixed and sintered to form a composite cathode material. 0.25 Mn 0.75 The (OH)2 nickel manganese compound material has a molar ratio of 1:1.02 to the lithium source. The sintering in step S04 is a second heat treatment process, in which the temperature range of the second heat treatment process is 300°C to 710°C, the treatment time of the second heat treatment process is 24 hours to 30 hours, and the temperature rise rate of the second heat treatment process is 2.5°C / min. As shown in Figure 1, the composite positive electrode material 1 includes a core layer 10 and a coating layer 20, and the core layer 10 is LiNi 0.5 Mn 1.5 O4, and a coating layer 20 covers the core layer 10, and the coating layer 20 is made of an LATP solid electrolyte material.

[0013] In this embodiment, in order to obtain an optimum solid electrolyte coating effect, Ni 0.25 Mn 0.75The weight percentage range of the LATP solid electrolyte material relative to the (OH)2 nickel manganese compound material is controlled to be 0.2 wt.% to 1.0 wt.%.

[0014] 4A to 4D are SEM images of the first comparative example. In the first comparative example, the positive electrode material was a lithium nickel manganese oxide (LMNO) (LiNi 0.5 Mn 1.5 O4) is not coated with the LATP solid electrolyte.

[0015] 5A to 5D are SEM images of a composite positive electrode material according to a first embodiment of the present invention. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material to the (OH)2 nickel manganese compound material was 0.2 wt.%, and a composite positive electrode material was prepared by steps S01 to S04.

[0016] 6A to 6D are SEM images of a composite positive electrode material according to a second embodiment of the present invention. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material to the (OH)2 nickel manganese compound material was 0.5 wt.%, and a composite positive electrode material was prepared by steps S01 to S04.

[0017] 7A to 7D are SEM images of a composite cathode material according to a third embodiment of the present invention. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material to the (OH)2 nickel manganese compound material was 1.0 wt.%, and a composite positive electrode material was prepared by steps S01 to S04.

[0018] Figure 8 shows the potential-capacity charge-discharge curves for the first comparative example, the first, second, and third examples of the present invention. These were measured at a 0.1C charge-discharge rate (C-rate) for the button batteries fabricated in the first comparative example, the first, second, and third examples of the present invention. The positive electrode sheet of the button battery is composed of a positive electrode material, a conductive agent, and a binder in a ratio of 94:4:2, and the negative electrode sheet is lithium metal. The button battery electrolyte contains 1.15 M lithium hexafluorophosphate (LiPF), ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and 5 wt% fluoroethylene carbonate (FEC). The 0.1C first-cycle and second-cycle charge-discharge capacity results are shown in Table 1. Table 1 also shows the performance results of the samples of the first comparative example and the first, second, and third examples of the present invention after charging at 0.2 C and discharging at 1 C, 2 C, 3 C, and 5 C. As shown in FIG. 8 and Table 1, the first, second, and third examples of the present invention all have better capacity and rate performance than the first comparative example. Therefore, the present invention is based on the dry mechanical mixing method to mix Ni 0.25 Mn 0.75 After mixing the (OH)2 nickel manganese compound material with the LATP solid electrolyte material, a lithium source is added, and then mixing and sintering processes are carried out to obtain a composite positive electrode material having a core layer and a coating layer, which is found to be helpful in improving the capacitance performance and rate performance of the lithium nickel manganese oxide positive electrode material LMNO. [Table 1]

[0019] FIG. 9 shows the capacity retention vs. cycle number discharge curves for the first comparative example, and the first, second, and third examples of the present invention. This was measured at a 1C charge / discharge rate (C-rate) for the button batteries manufactured in the first comparative example, the first, second, and third examples of the present invention. As shown in FIG. 9, the capacity retention rates of the first to third examples of the present invention are all superior to that of the first comparative example. Therefore, the use of the composite positive electrode material formed by the manufacturing method of the present invention can improve the cycle performance of the lithium nickel manganese oxide positive electrode material LMNO and extend its cycle life.

[0020] 10 is a flowchart of a method for manufacturing a composite positive electrode material according to a second embodiment of the present invention. In this embodiment, a nickel-manganese compound material is first provided, and the nickel-manganese compound material is Ni 0.25 Mn 0.75 In this embodiment, Ni 0.25 Mn 0.75 O is Ni 0.25 Mn 0.75 (OH)2 is formed by pre-oxidation treatment. As shown in step S00', Ni 0.25 Mn 0.75 (OH)2 is obtained, and a pre-oxidation process is carried out to obtain Ni 0.25 Mn 0.75 O. Ni 0.25 Mn 0.75 O nickel manganese compound material can be obtained, and the Ni 0.25 Mn 0.75 O. Ni 0.25 Mn 0.75 The nickel manganese compound material has an average particle size of 10 μm to 20 μm, for example, 13.96 μm, and a surface area of ​​20.49 m 2 The temperature range of the pre-oxidation process is 300°C to 850°C, the treatment time of the pre-oxidation process is 5 hours to 7 hours, and the temperature rise rate of the pre-oxidation process is 2.5°C / min. In another embodiment, Ni 0.25 Mn 0.75The lithium aluminum titanium phosphate (LATP) solid electrolyte material is prepared as shown in step S02', and NiO is obtained by other processes, and the present invention is not limited thereto. 0.25 Mn 0.75 The O nickel manganese compound material and LATP solid electrolyte material are mixed by dry mechanical fusion method to form a composite material. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material relative to the nickel-manganese compound material is 0.2 wt.% to 1.0 wt.%. In step S02', mechanically mixing the nickel-manganese compound material and the solid electrolyte includes mixing at a rotation speed of 700 rpm for 5 minutes, mixing at a rotation speed of 1400 rpm for 5 minutes, mixing at a rotation speed of 2100 rpm for 5 minutes, mixing at a rotation speed of 2800 rpm for 10 minutes, and mixing at a rotation speed of 3500 rpm for 10 minutes. The operating temperature for mechanically mixing the nickel-manganese compound material and the solid electrolyte is 25°C to 45°C. After the mechanical mixing, a first heat treatment process is performed (step S03'). The temperature range of the first heat treatment process is 300°C to 750°C, the treatment time of the first heat treatment process is 5 hours to 7 hours, and the heating rate of the first heat treatment process is 2.5°C / min.

[0021] Next, as shown in step S04', a lithium source, such as lithium hydroxide, is provided, and the lithium source and the composite material are mixed and sintered to form a composite cathode material. 0.25 Mn 0.75 The molar ratio of the nickel manganese compound material to the lithium source is 1:1.02. The sintering in step S04' is a second heat treatment process, in which the temperature range is 300°C to 710°C, the treatment time is 24 hours to 30 hours, and the temperature rise rate is 2.5°C / min. As shown in Figure 1, the composite positive electrode material 1 includes a core layer 10 and a coating layer 20, and the core layer 10 is made of LiNi 0.5 Mn 1.5O4, and the coating layer 20 covers the core layer 10, and the coating layer 20 is made of LATP solid electrolyte material.

[0022] In this embodiment, in order to obtain an optimum solid electrolyte coating effect, Ni 0.25 Mn 0.75 The weight percentage range of the LATP solid electrolyte material relative to the O nickel manganese compound material is controlled to be 0.2 wt.% to 1.0 wt.%.

[0023] 11A to 11D are SEM images of a composite positive electrode material according to a fourth embodiment of the present invention. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material to the O nickel manganese compound material was 0.2 wt.%, and a composite positive electrode material was prepared by the steps S01' to S04'.

[0024] 12A to 12D are SEM images of a composite positive electrode material according to a fifth embodiment of the present invention. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material to the O nickel manganese compound material was 0.3 wt.%, and a composite positive electrode material was prepared by the steps S01' to S04'.

[0025] 13A to 13D are SEM images of a composite positive electrode material according to a sixth embodiment of the present invention. 0.25 Mn 0.75 The weight percentage of the LATP solid electrolyte material to the O nickel manganese compound material was 0.5 wt.%, and a composite positive electrode material was prepared by the steps S01' to S04'.

[0026] Figure 14 shows the potential-capacity charge-discharge curves for the first comparative example, the fourth, fifth, and sixth examples of the present invention. These were measured at a 0.1C charge-discharge rate (C-rate) for the button batteries fabricated in the first comparative example, the fourth, fifth, and sixth examples of the present invention. The positive electrode sheet of the button battery is composed of a positive electrode material, a conductive agent, and a binder in a ratio of 94:4:2, and the negative electrode sheet is lithium metal. The button battery electrolyte contains 1.15 M lithium hexafluorophosphate (LiPF), ethylene carbonate (EC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and 5 wt% fluoroethylene carbonate (FEC). The 0.1C first-cycle and second-cycle charge-discharge capacity results are shown in Table 2. Table 2 also shows the rate performance results after the samples of the first comparative example and the fourth, fifth, and sixth examples of the present invention were charged for 0.2 seconds and discharged at 1C, 2C, 3C, and 5C. As shown in FIG. 14 and Table 2, the capacity and rate performance of the fourth, fifth, and sixth examples of the present invention are all superior to the capacity and rate performance of the first comparative example. Therefore, it is believed that the dry mechanical mixing method used in the present invention can produce Ni 0.25 Mn 0.75 After mixing the O nickel manganese compound material with the LATP solid electrolyte material, a lithium source is added and mixed, and then sintering is performed to form a composite positive electrode material having a core layer and a coating layer, which can improve the capacity performance and rate performance of the lithium nickel manganese oxide positive electrode material LMNO. [Table 2]

[0027] FIG. 15 shows room-temperature 1C cycle life curves for the first comparative example, and the fourth, fifth, and sixth examples of the present invention. These were measured at a 1C charge / discharge rate (C-rate) for the button batteries manufactured in the first comparative example, the fourth, fifth, and sixth examples of the present invention. As shown in FIG. 15, the capacity retention rates of the fourth to sixth examples of the present invention are all superior to that of the first comparative example. Therefore, the use of a composite positive electrode material formed by the manufacturing method of the present invention can improve the cycle performance of the lithium nickel manganese oxide positive electrode material LMNO and extend its cycle life.

[0028] As described above, the present invention is characterized in that the LATP solid electrolyte material is Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 By controlling the weight percentage of the nickel manganese compound material such as O to the range of 0.2 wt.% to 1.0 wt.%, a composite positive electrode material with excellent coating effect can be obtained. 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 It is more preferable to set the weight percentage of the LATP solid electrolyte material to 0.2 wt.% to 0.3 wt.% relative to the nickel manganese compound material, such as O. In other words, the present invention can form a coating layer that improves the rate performance of the lithium nickel manganese oxide positive electrode material LMNO simply by adding a small amount of lithium aluminum titanium phosphate LATP solid electrolyte, further reducing manufacturing costs and achieving an optimal solid electrolyte coating effect. On the other hand, the composite positive electrode material of the present invention forms the lithium nickel manganese oxide positive electrode material LMNO by mixing lithium aluminum titanium phosphate (LATP) into a pretreatment material for the lithium nickel manganese oxide positive electrode material LMNO. The pretreatment material can be, for example, Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75O nickel manganese compound material, and the coating process does not directly use the lithium nickel manganese oxide positive electrode material LMNO.

[0029] In the second comparative example, the lithium nickel manganese oxide positive electrode material LMNO was obtained, and 0.2 wt.% LATP solid electrolyte material was added. The average particle diameter of the lithium nickel manganese oxide positive electrode material LMNO was about 15.13 μm, and the surface area was 0.31 m 2 / g. The second comparative example can be obtained by coating the LATP solid electrolyte material on the surface of the lithium nickel manganese oxide positive electrode material LMNO using the same mixing method.

[0030] In the third comparative example, a lithium nickel manganese oxide positive electrode material LMNO was obtained, and 0.2 wt.% LATP solid electrolyte material was added. The average particle diameter of the lithium nickel manganese oxide positive electrode material LMNO was about 15.13 μm, and the surface area was 0.31 m 2 The third comparative example can be obtained by coating the LATP solid electrolyte material on the surface of the lithium nickel manganese oxide positive electrode material LMNO using the same mixing method, and then performing a sintering process.

[0031] FIG. 16 shows the potential-capacity charge-discharge curves of Comparative Example 2, Comparative Example 3, Example 1 of the present invention, and Example 4. This was measured at a 0.1C charge-discharge rate (C-rate) for the button batteries fabricated in Comparative Example 2, Comparative Example 3, Example 1 of the present invention, and Example 4. The 0.1C first-cycle and second-cycle charge-discharge capacity results are shown in Table 3. Table 3 also shows the rate performance results after 0.2C charging and 1C / 2C / 3C / 5C discharging for the samples of Comparative Example 2, Comparative Example 3, Example 1 of the present invention, and Example 4. As shown in FIG. 16 and Table 3, the capacity and rate performance of Example 1 and Example 4 of the present invention are both superior to those of Comparative Example 2 and Comparative Example 3. Therefore, when a composite cathode material is used, which is prepared by mixing a nickel manganese compound material and an LATP solid electrolyte material using a dry mechanical mixing method, adding a lithium source, mixing, and then sintering, as in the present invention, the capacitance and rate performance are superior to those obtained by directly coating an LATP solid electrolyte material on a lithium nickel manganese oxide cathode material, LMNO. [Table 3]

[0032] FIG. 17 is a room-temperature 1C cycle life curve diagram for the third comparative example, the first example of the present invention, and the fourth example. This was measured at a 1C charge / discharge rate (C-rate) for the button batteries manufactured in the third comparative example, the first example of the present invention, and the fourth example of the present invention. As shown in FIG. 17, the capacity retention rates of the first and fourth examples of the present invention are all superior to that of the third comparative example. Furthermore, the cycle life after 200 cycles of the first and fourth examples of the present invention was increased by 10% compared to the third comparative example. Therefore, in the method of the present invention, in which lithium aluminum titanium phosphate (LATP) is mixed into the pretreatment material of the lithium nickel manganese oxide cathode material LMNO by a mechanical method, for example, the mechanofusion method, Mn 3+Reduces the formation of Mn 3+ This can prevent the dissolution of the positive electrode material, reduction and deposition on the negative electrode, and the resulting electrical deterioration during cycling.

[0033] The present invention utilizes a dry mechanofusion method to mix nickel manganese compound material with a solid electrolyte and completes the surface coating of the solid electrolyte simultaneously with the heat treatment of the lithium manganese oxide cathode material LMNO. This allows for a simple and rapid manufacturing process, and the resulting composite cathode material reliably improves the performance of the cathode material, which is superior to directly coating the lithium manganese oxide cathode material LMNO with a solid electrolyte. To achieve optimal solid electrolyte coating, the present invention adds only a small amount of lithium aluminum titanium phosphate (LATP) solid electrolyte to form a coating layer that improves the rate performance of the lithium nickel manganese oxide cathode material LMNO, further reducing manufacturing costs. By controlling the mixing method, operating temperature, rotation speed, and time of the lithium aluminum titanium phosphate (LATP) and pretreatment material, structural defects in the solid electrolyte coating layer due to high temperatures or excessive friction between particles can be prevented. At the same time, the LATP solid electrolyte coating allows the lithium nickel manganese oxide cathode material LMNO to exhibit low impedance and good charge / discharge performance. Of course, the Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 O nickel manganese compound material, lithium aluminum titanium phosphate (Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LATP) solid electrolyte, and lithium nickel manganese oxide cathode material (LiNi 0.5 Mn 1.5 The composition of O4, LMNO can be adjusted according to actual demand. For example, Ni x Mn y (OH)2 or Ni x Mn y LiO nickel manganese compound material 1+z Al z Ti2-z Lithium aluminum titanium phosphate (Li) can also be obtained by mixing it with a (PO4)3 solid electrolyte (where x + y = 1, z ≦ 2), then adding a lithium source, mixing, and sintering. 1+z Al z Ti 2-z (PO4)3) is used as a lithium nickel manganese oxide cathode material, LiNi 2x Mn 2y A composite cathode material coated on the surface of O4 can be obtained, the details of which are omitted here.

[0034] As described above, the present invention provides a method for manufacturing a composite positive electrode material, which uses a dry mechanofusion method to process a precursor and a solid electrolyte to form a positive electrode material, while simultaneously completing the surface coating of the solid electrolyte. This makes the manufacturing process simple and fast, and effectively improves the performance of the positive electrode material. The positive electrode material, lithium nickel manganese oxide (LMNO), is mixed with lithium aluminum titanium phosphate (Li 1.3 Al 0.3 Ti 1.7 The present invention uses a dry mechanical mixing method to coat the (PO4)3,LATP) solid electrolyte, and Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 A composite positive electrode material having a core layer and a coating layer can be formed by first mixing the nickel manganese compound material of O with the solid electrolyte material, then adding a lithium source, mixing, and sintering. The inner core layer is LiNi 0.5 Mn 1.5O4, and the outer coating layer is made of a solid electrolyte material. Because the lithium aluminum titanium phosphate (LATP) solid electrolyte has inherently excellent ion conductivity properties, when it coats the surface of the lithium nickel manganese oxide cathode material LMNO to form a composite cathode material, it helps improve the rate performance and cycle performance of the lithium nickel manganese oxide cathode material LMNO. The lithium aluminum titanium phosphate (LATP) coating layer also provides a protective function that delays the damage to the material surface caused by the electrolyte. In addition, to achieve the optimal solid electrolyte coating effect, the solid electrolyte material is made of Ni 0.25 Mn 0.75 (OH)2 or Ni 0.25 Mn 0.75 The weight percentage of the lithium manganese compound material, such as Mn, is controlled to 0.2 wt.% to 1.0 wt.%, and more preferably to 0.2 wt.% to 0.3 wt.%. That is, in the present invention, by simply adding a small amount of lithium aluminum titanium phosphate (LATP) solid electrolyte, a coating layer that improves the rate performance of the lithium nickel manganese oxide positive electrode material LMNO can be formed, further reducing manufacturing costs. Rather than directly coating the lithium nickel manganese oxide positive electrode material LMNO with lithium aluminum titanium phosphate (LATP), the present invention uses a mechanical method, for example, a mechanofusion method, to mix lithium aluminum titanium phosphate (LATP) into a pre-treatment material for the lithium nickel manganese oxide positive electrode material LMNO to form the lithium nickel manganese oxide positive electrode material LMNO. Therefore, Mn 3+ The production of Mn 3+This prevents the dissolution of lithium from the positive electrode material, its reduction and deposition on the negative electrode, and its subsequent electrical degradation during cycling. The mixing process is typically performed at temperatures between 25°C and 45°C, with rotation speeds between 700 rpm and 3500 rpm, for 5 to 30 minutes in stages. By controlling the mixing method, operating temperature, rotation speed, and time of the lithium aluminum titanium phosphate (LATP) and pretreatment material, structural defects in the solid electrolyte coating layer caused by high temperatures or excessive friction between particles can be prevented. At the same time, the lithium nickel manganese oxide positive electrode material LMNO exhibits low impedance and good charge / discharge performance due to the LATP solid electrolyte coating.

[0035] The present invention can be modified or changed in various ways by those skilled in the art, but all such modifications and changes are within the scope of the claims of the present invention without departing from the technical idea of ​​the present invention. [Explanation of symbols]

[0036] 1: Composite cathode material 10: Core layer 11: Li+ ions 20: Covering layer 30: Electrolyte S01~S04, S00'~S04': Step

Claims

1. 1. A method for producing a composite positive electrode material, comprising: A nickel manganese compound material is provided, the nickel manganese compound material comprising Ni ｘ Mn ｙ (OH) ２ or Ni ｘ Mn ｙ O and x+y=1; Step (b) providing a solid electrolyte material, and mixing the nickel manganese compound material and the solid electrolyte material by mechanical mixing to form a composite material, wherein the weight percentage of the solid electrolyte material to the nickel manganese compound material is 0.2 wt. % to 1.0 wt. %; providing a lithium source, mixing the lithium source with the composite material, and sintering to form the composite positive electrode material, the composite positive electrode material comprising a core layer and a coating layer, the core layer comprising LiNi ２ｘ Mn ２ｙ O ４ wherein the coating layer covers the core layer, and the coating layer is composed of the solid electrolyte material.

2. The nickel manganese compound material is Ni ０．２５ Mn ０．７５ (OH) ２ and in step (b), after the mechanical mixing, a first heat treatment process is performed, the temperature range of the first heat treatment process is 300°C to 850°C, the treatment time of the first heat treatment process is 5 hours to 7 hours, and the temperature rising rate of the first heat treatment process is 2.5°C / min.

3. The nickel manganese compound material is Ni ０．２５ Mn ０．７５ 2. The method for producing a composite positive electrode material according to claim 1, wherein the temperature range of the pre-oxidation process is 300°C to 850°C, the treatment time of the pre-oxidation process is 5 hours to 7 hours, and the temperature rise rate of the pre-oxidation process is 2.5°C / min.

4. 4. The method for manufacturing a composite positive electrode material according to claim 3, wherein in step (b), after the mechanical mixing, a first heat treatment process is performed, the temperature range of the first heat treatment process is 300°C to 750°C, the treatment time of the first heat treatment process is 5 hours to 7 hours, and the temperature rising rate of the first heat treatment process is 2.5°C / min.

5. 2. The method of claim 1, wherein in step (b), the process of mechanically mixing the nickel manganese compound material and the solid electrolyte includes mixing at a rotation speed of 700 rpm for 5 minutes, at a rotation speed of 1400 rpm for 5 minutes, at a rotation speed of 2100 rpm for 5 minutes, at a rotation speed of 2800 rpm for 10 minutes, and at a rotation speed of 3500 rpm for 10 minutes.

6. 2. The method for manufacturing a composite positive electrode material according to claim 1, wherein in step (b), the operating temperature of mixing the nickel manganese compound material and the solid electrolyte by the mechanical method is 25°C to 45°C.

7. The chemical formula of the solid electrolyte is Li １＋ｚ Al ｚ Ti ２－ｚ (P.O. ４ ) ３ 2. The method of claim 1, wherein z is less than or equal to 2.

8. The method for manufacturing a composite positive electrode material according to claim 1 , wherein the mechanical method comprises a mechanical fusion method.

9. 2. The method of claim 1, wherein in step (c), the process of mechanically mixing the lithium source and the composite material comprises mixing at a rotation speed of 700 rpm for 5 minutes and then at a rotation speed of 1400 rpm for 30 minutes.

10. 2. The method for producing a composite positive electrode material according to claim 1, wherein step (c) includes a second heat treatment process, the temperature range of the second heat treatment process is 300°C to 710°C, the treatment time of the second heat treatment process is 24 hours to 30 hours, and the temperature rising rate of the second heat treatment process is 2.5°C / min.

11. 2. The method for producing a composite positive electrode material according to claim 1, wherein in step (c), the molar ratio of the nickel manganese compound material to the lithium source in the composite material is 1:1.

02.

12. 2. The method of claim 1, wherein the weight percentage is 0.2 wt. % to 0.3 wt. %.

13. 2. The method for producing a composite positive electrode material according to claim 1, wherein the nickel-manganese compound material has an average particle size of 10 μm to 20 μm, and the solid electrolyte material has an average particle size of 1 μm to 5 μm.

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