Composite ternary material and preparation method thereof

Abstract

The present application relates to a kind of composite ternary material and its preparation method, it relates to lithium ion battery positive electrode material technical field, the composite ternary material is the composite material of lithium manganese iron phosphate coated ternary material, the inner layer of the composite material is ternary material LiaNibCocMndRxO2, wherein 0.8≤a≤1.05, 0.5≤b≤0.95, 0.05≤c≤0.35, 0≤d≤0.3, 0≤x≤0.15, b+c+d+x=1.The present application uses lithium manganese iron phosphate to mix nickel cobalt lithium manganate after one or more sintering, the material after coating mixing is sintered at low temperature, utilizes solid solution formed by body phase doping on the surface of ternary material, tightly combines lithium manganese iron phosphate material and ternary material, and simultaneously adds fast ion conductor to coat, improves the conductivity of composite material, to ensure that composite material and high capacity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium ion battery cathode material, and particularly relates to a composite ternary material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the large-scale application of new energy vehicles, new energy vehicle fire accidents have attracted social attention, and become an important factor affecting the high-quality development of the new energy vehicle industry. The safety problem of electric vehicles needs to be solved. As the mainstream cathode material, ternary material is favored in the medium and high-end electric vehicle market due to its high energy density and excellent low-temperature activity.

[0003] However, due to the active layered lattice structure of ternary material, its thermal stability is poor, and it will decompose at about 300 DEG C and release oxygen molecules. With the increase of nickel content, the unstable Ni 3+ proportion in the material increases, which is easy to react with moisture and carbon dioxide in the air, and the thermal stability decreases.

[0004] The thermal decomposition temperature of lithium manganese iron phosphate is about 600 DEG C, which is much higher than that of ternary material. By mixing lithium manganese iron phosphate with ternary material, the safety performance of the material can be balanced. However, the conventional stirring process has limited effect on improving the safety of ternary material, and the poor conductivity, rate performance and processing performance of lithium manganese iron phosphate lead to the decrease of the conductivity and processing performance of ternary material after stirring and mixing. SUMMARY

[0005] To solve the above problems, the present application provides a composite ternary material and a preparation method thereof.

[0006] In a first aspect, the present application provides a composite ternary material, which is a composite material of lithium manganese iron phosphate coated ternary material. The inner layer of the composite material is a ternary material LiaNibCocMndRxO2, wherein 0.8≤a≤1.05, 0.5≤b≤0.95, 0.05≤c≤0.35, 0≤d≤0.3, 0≤x≤0.15, and b+c+d+x=1. R is at least one of Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, and Zr.

[0007] Further, the outer shell of the composite material is at least one of lithium manganese iron phosphate and a compound containing M element; the M element is at least one of Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, and Zr, and a fast ion conductor.

[0008] In a second aspect, the present application provides a preparation method of the composite ternary material according to any one of the first aspect, which comprises the following steps:

[0009] Mixing one or more of a ternary precursor, a lithium source, and a compound containing an R element to obtain a first mixture;

[0010] Performing first sintering on the first mixture under an oxygen atmosphere, and then crushing to obtain a second mixture;

[0011] Uniformly dispersing a fast ion conductor material in a LiOH aqueous solution, and then adding the second mixture to perform ball milling to obtain a third mixture;

[0012] Mixing and coating the third mixture, a lithium manganese iron phosphate, and a compound containing an M element to obtain a fourth mixture;

[0013] Performing second sintering on the fourth mixture, and then crushing to obtain a fifth mixture;

[0014] Mixing and coating the fifth mixture and the lithium manganese iron phosphate to obtain the composite ternary material.

[0015] Further, the working condition parameters of the first sintering include a sintering temperature of 800-940 DEG C and a sintering period of 9-32 h.

[0016] Further, the working condition parameters of the second sintering include a sintering temperature of 200-500 DEG C and a sintering period of 3-10 h.

[0017] Further, the ternary precursor includes Ni 0.67 Co 0.05 Mn 0.28 (OH)2.

[0018] Further, the fast ion conductor material includes LATP.

[0019] The above technical solution provided by the embodiment of the present application has at least the following advantages compared with the prior art:

[0020] The embodiment of the present application provides a composite ternary material and a preparation method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0021] The drawings incorporated into the specification and forming a part thereof, illustrate embodiments consistent with the present application and together with the description serve to explain the principles of the present application.

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0023] Figure 1 An SEM characterization diagram of a composite ternary material provided for the embodiment 1 of the present application.

[0024] Figure 2 An SEM characterization diagram of a composite ternary material provided for the embodiment 2 of the present application.

[0025] Figure 3 A charge-discharge curve diagram of a composite ternary material provided for the embodiment 1 of the present application.

[0026] Figure 4 A charge-discharge curve diagram of a composite ternary material provided for the embodiment 2 of the present application.

[0027] Figure 5 A charge-discharge curve diagram of a composite ternary material provided for the comparative example 1 of the present application.

[0028] Figure 6 A charge-discharge curve diagram of a composite ternary material provided for the comparative example 2 of the present application. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0030] Unless otherwise specifically indicated, all the various raw materials, reagents, instruments and equipment and the like used in the present application can be purchased from the market or can be prepared by the existing methods.

[0031] In a first aspect, the present application provides a composite ternary material, which is a composite material of a lithium iron manganese phosphate coated ternary material, and an inner layer of the composite material is a ternary material LiaNibCocMndRxO2, wherein 0.8≤a≤1.05, 0.5≤b≤0.95, 0.05≤c≤0.35, 0≤d≤0.3, 0≤x≤0.15, b+c+d+x=1; and R is at least one of Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, Zr.

[0032] The embodiment of the present application provides a kind of composite ternary material, the present application uses lithium manganese iron phosphate to mix lithium nickel manganese oxide after one or more sintering, the material after coating mixing is sintered at low temperature, utilize bulk doping to form solid solution on the surface of ternary material, lithium manganese iron phosphate material and ternary material are closely combined together, and fast ion conductor is added simultaneously to make coating, improve the conductivity of composite material, to ensure that composite material high safety and high capacity.

[0033] A kind of lithium manganese iron phosphate coated ternary material composite, its inner layer is ternary material LiaNibCocMndRxO2, wherein 0.8≤a≤1.05, 0.5≤b≤0.95, 0.05≤c≤0.35, 0≤d≤0.3, 0≤x≤0.15, b+c+d+x=1;R is one or more of compound containing Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, Zr and the like, the lithium source involved uses the lithium salt of industry conventional kind. Shell is lithium manganese iron phosphate, at least one of compound containing M element (Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, Zr and the like), and fast ion conductor (primary particle 200-800nm).

[0034] 1, one or more of ternary precursor, lithium source, R element-containing compound is mixed at high speed;

[0035] 2, the material after mixing is sintered in oxygen atmosphere, sintering temperature is 800-940 DEG C, sintering period is 9-32h, and the sintered material is crushed;

[0036] 3, 0.1wt%-5wt%LiOH is weighed and prepared into solution (0.5-1.0:1) with deionized water, 0.5wt%-1.5wt% fast ion conductor material (such as LATP fast ion conductor material, i.e. lithium aluminum titanium phosphate) is uniformly dispersed in LiOH solution, then the intermediate product is mixed with the prepared solution, ball milling is mixed, which can reduce the particle size of fast ion conductor and improve the coating effect;

[0037] 4, the material after ball milling is coated with a small amount of lithium manganese iron phosphate and at least one of M element-containing compound (M is Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, Zr and the like) in mixing machine;

[0038] 5, the material after coating is sintered in compressed air or inert protective gas, sintering temperature is 200-500 DEG C, sintering period is 3-10h;

[0039] After crushing the secondary sintered material, 8wt%-15wt% lithium manganese iron phosphate is coated in a fusion machine to uniformly coat the lithium manganese iron phosphate on the surface of the material to obtain a composite material.

[0040] It should be noted that the component raw materials involved in the composite ternary material and the preparation method thereof provided in the embodiments of the present application can be directly used as commercially available products or self-made by using the existing public preparation method if there is no special limitation or specific description. Meanwhile, the steps and parameters involved can be processed according to the existing processing technology of the composite ternary material or directly using the existing equipment if there is no special limitation or specific description, and the present application document will not be described one by one.

[0041] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods in the following examples without specific conditions are generally determined according to the national standards. If there is no corresponding national standard, the general international standard, the conventional condition or the condition suggested by the manufacturer is used.

[0042] Example 1

[0043] The present example provides a composite ternary material, comprising the following steps:

[0044] 1. Selecting the precursor as Ni 0.67 Co 0.05 Mn 0.28 (OH)2, and mixing the precursor, lithium carbonate, oxide containing Zr, Y and W, and phosphate containing La in a high-speed mixer according to Li / M=1.02;

[0045] 2. Sintering the mixed material at 935℃ for 10-15h in an oxygen atmosphere, and crushing the sintered material;

[0046] 3. Preparing a 1:2 solution of 2.2wt% LiOH with deionized water, dispersing 1wt% LATP in the solution, and ball-milling the crushed material with the prepared solution for 30min;

[0047] 4. High-speed mixing and coating the ball-milled material with 1.5wt% lithium manganese iron phosphate and oxide containing Al, Ti and B;

[0048] 5. Sintering the coated material at 470℃ for 9h in compressed air;

[0049] 6. Crushing the secondary sintered material, adding 13.5wt% lithium manganese iron phosphate after sieving, and performing fusion coating.

[0050] The SEM characterization graph of the composite ternary material obtained in the present example is as follows:Figure 1 as shown.

[0051] Example 2

[0052] The example provides a composite ternary material, comprising the following steps:

[0053] 1. Selecting the precursor as Ni 0.67 Co 0.05 Mn 0.28 (OH)2, and mixing the precursor, lithium carbonate, oxides containing Zr, Y, and W, and phosphate containing La in a high-speed mixer according to Li / M=1.01;

[0054] 2. Sintering the mixed material at 935°C for 10-15h in an oxygen atmosphere, and crushing the sintered material;

[0055] 3. Preparing a 1:2 solution of 3wt% LiOH with deionized water, dispersing 0.5wt% LATP in the solution, and ball-milling the crushed material and the prepared solution for 30min;

[0056] 4. High-speed mixing and coating the ball-milled material with 1.5wt% manganese iron phosphate, and oxides containing Al, Ti, and B;

[0057] 5. Sintering the coated material at 470°C for 9h in compressed air;

[0058] 6. Crushing the twice-sintered material, adding 13.5wt% manganese iron phosphate, and fusing and coating.

[0059] The SEM characterization diagram of the composite ternary material obtained in the example is as shown. Figure 2

[0060] Comparative Example 1

[0061] The example provides a composite ternary material, which is coated by a dry method, comprising the following steps:

[0062] 1. Selecting the precursor as Ni 0.67 Co 0.05 Mn 0.28 (OH)2, and mixing the precursor, lithium carbonate, oxides containing Zr, Y, and W, and phosphate containing La in a high-speed mixer according to Li / M=1.02;

[0063] 2. Sintering the mixed material at 935°C for 10-15h in an oxygen atmosphere, and crushing the sintered material;

[0064] 3. High-speed mixing and coating with 2.2wt% LiOH, 1wt% LATP, 1.5wt% manganese iron phosphate, and oxides containing Al, Ti, and B;​

[0065] 4. Sintering the coated material at 470°C for 9h under compressed air;

[0066] 5. Crushing the twice-sintered material, adding 13.5wt% lithium manganese phosphate to fuse and coat.

[0067] This example uses dry coating of LATP, and there is obvious residue after 400 mesh sieving. The effect of the voltage test is lower than that of wet coating.

[0068] Comparative Example 2

[0069] This example provides a composite ternary material using a conventional lithium ratio, including the following steps:

[0070] 1. Selecting the precursor Ni 0.67 Co 0.05 Mn 0.28 (OH)2, and mixing the precursor, lithium carbonate, oxides containing Zr, Y, and W, and phosphate containing La in a high-speed mixer according to Li / M=1.05;

[0071] 2. Sintering the mixed material at 935°C for 10-15h under an oxygen atmosphere, and crushing the sintered material;

[0072] 3. Dispersing 1wt% LATP in 4wt% deionized water, and then ball-milling the crushed material with the prepared solution for 30min;

[0073] 4. High-speed mixing the ball-milled material with 1.5wt% lithium manganese phosphate and oxides containing Al, Ti, and B for coating;

[0074] 5. Sintering the coated material at 470°C for 9h under compressed air;

[0075] 6. Crushing the twice-sintered material, and adding 13.5wt% lithium manganese phosphate to fuse and coat.

[0076] Test Example

[0077] This example tests the performance of the composite ternary materials provided in Examples 1-2 and Comparative Examples 1-2, and the test results are shown in Figures 3-6 and Tables 1, 2, and 3.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] Table 3

[0083]

[0084] Various embodiments of the application can exist in a variety of forms; it should be understood that the description of the embodiments in a range format is merely for convenience and brevity and should not be construed as limiting the scope of the application to a narrower range; accordingly, it should be understood that the description in range format includes and covers all the sub-ranges of the ranges described; for example, descriptions in the range of from 1 to 6 should be considered to include sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc.; and also includes single numbers within the range, for example, 1, 2, 3, 4, 5, and 6, etc. in this same manner. Also, whenever a numerical range is indicated, it is meant to include any cited numeral (fractional or integral) within the indicated range.

[0085] The previous description is of a specific embodiment of the application and the skilled person will be able to understand or implement the application from this description. Numerous modifications to these embodiments will be apparent to those skilled in the art and the general principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the application is not to be limited to the embodiments shown herein but is to be accorded the broadest scope consistent with the principles and novel features shown herein.

Claims

1. A composite ternary material, characterized in that, The composite ternary material is a composite material of lithium manganese iron phosphate coated ternary material, and an inner layer of the composite material is a ternary material LiaNibCocMndRxO2, wherein 0.8≤a≤1.05, 0.5≤b≤0.95, 0.05≤c≤0.35, 0≤d≤0.3, 0≤x≤0.15, and b+c+d+x=1; R is at least one of Al, Ti, Mg, Sr, Y, W, B, Nb, La, Ta, Mo, and Zr; The preparation method of the composite ternary material comprises the following steps: mixing one or more of a ternary precursor, a lithium source, and a compound containing an R element to obtain a first mixture; performing first sintering on the first mixture in an oxygen atmosphere, and then crushing to obtain a second mixture; uniformly dispersing a fast ion conductor material in a LiOH aqueous solution, and then adding the second mixture to perform ball milling to obtain a third mixture; mixing and coating the third mixture, lithium manganese iron phosphate, and a compound containing an M element to obtain a fourth mixture; the compound containing the M element is an oxide containing Al, Ti, and B; performing second sintering on the fourth mixture, and then crushing to obtain a fifth mixture; the working condition parameters of the second sintering include a sintering temperature of 200-500 ℃ and a sintering cycle of 3-10 h; mixing and coating the fifth mixture and lithium manganese iron phosphate to obtain the composite ternary material; the working condition parameters of the first sintering include a sintering temperature of 800-940 ℃ and a sintering cycle of 9-32 h.

2. The composite ternary material of claim 1, wherein, The ternary precursor includes Ni 0.67 Co 0.05 Mn 0.28 (OH)2.

3. The composite ternary material of claim 2, wherein, The fast ion conductor material comprises LATP.

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