Preparation method of composite lithium supplement additive Li5FeO4-coated Li2NiO2

Abstract

The invention discloses a preparation method of a composite lithium supplement additive Li5FeO4-coated Li2NiO2, and belongs to the technical field of lithium ion batteries. The method comprises the following steps: 1, uniformly mixing iron oxide powder and lithium source powder to obtain a powdery mixture; sintering the powdery mixture in an inert gas atmosphere, cooling, crushing and sieving to obtain a Li5FeO4 lithium supplement additive of which the outer layer is coated with a lithium source; 2, uniformly mixing the prepared Li5FeO4 lithium supplement additive of which the outer layer is coated with a lithium source with a nickel source to obtain a powdery mixture; and sintering the mixture in an inert gas atmosphere, cooling, crushing and sieving to obtain the composite lithium supplement additive Li5FeO4-coated Li2NiO2. According to the prepared composite lithium supplement additive Li5FeO4-coated Li2NiO2, the conductivity of the monomer Li5FeO4 is greatly improved, and the first efficiency and the rate capability of the lithium ion battery are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a method for preparing a composite lithium supplement additive Li5FeO4@Li2NiO2. Background Art

[0002] With the improvement of people's living standards and the rapid development of science and technology, electric products such as power tools and electric vehicles are becoming increasingly popular. Lithium-ion batteries, as the primary power source for these products, play an irreplaceable role. However, during the initial charge and discharge process of lithium-ion batteries, a solid electrolyte film (SEI) forms on the surface of the negative electrode. This SEI film consumes the lithium ions released by the positive electrode, causing the initial capacity of the lithium-ion battery to drop sharply.

[0003] In the prior art, patent CN 117996051 A (High-capacity, cyclically stable positive electrode lithium-replenishing material, preparation method thereof, and application thereof) provides a high-capacity, cyclically stable positive electrode lithium-replenishing material, comprising: uniformly mixing a lithium salt, a first metal oxide, and a second metal oxide, and performing two-stage sintering under an inert atmosphere.

[0004] Patent CN 119153701 A (lithium-supplementing material and preparation method thereof, positive electrode material and secondary battery) discloses a lithium-supplementing material comprising a first lithium-rich material and a second lithium-rich material connected to each other.

[0005] Patent CN 118486826 A (A carbon quantum dot-coated Li5FeO4 lithium supplement, its preparation method and application) discloses that carbon quantum dots, an iron source and a lithium source are ball-milled and mixed uniformly, and then dried to obtain a powdered mixture; the powdered mixture is first pre-fired in an inert gas atmosphere, then sintered at a high temperature, and then pulverized after cooling to obtain a carbon quantum dot-coated Li5FeO4 lithium supplement.

[0006] The above patents all provide lithium supplement materials, but there is a common problem of complex raw material usage. Secondly, the battery capacity that can be achieved in the above patents is generally not high, and rarely exceeds 700mAh / g. Summary of the Invention

[0007] Technical issues

[0008] Lithium-supplementing materials currently have the common problems of complex raw material usage and little improvement in lithium-ion battery capacity. Therefore, it is necessary to provide a lithium-supplementing additive with a small number of raw materials, simple processing technology and excellent effect on improving battery capacity.

[0009] Technical Solution

[0010] In order to solve the above problems, the present invention provides a preparation method of a composite lithium supplement additive Li5FeO4@Li2NiO2, comprising the following steps:

[0011] (1) uniformly mixing iron oxide powder and lithium source powder to obtain a powdery mixture; sintering the powdery mixture in an inert gas atmosphere, and then cooling, crushing, and sieving to obtain a Li5FeO4 lithium supplement additive with an outer layer coated with a lithium source;

[0012] (2) The prepared Li5FeO4 lithium supplement additive with a lithium source wrapped in an outer layer is mixed evenly with a nickel source to obtain a powdered mixture; the mixture is sintered in an inert gas atmosphere, and then cooled, crushed, and sieved to obtain a composite lithium supplement additive Li5FeO4@Li2NiO2.

[0013] Furthermore, the particle size of the iron oxide powder in step (1) is in the range of 50-100 nm.

[0014] Furthermore, the lithium source powder in step (1) is one or a mixture of Li(NO3)2, Li2O, LiOH, LiOH·H2O, and Li2CO3.

[0015] Preferably, the lithium source powder in step (1) is one or a mixture of Li(NO3)2, Li2O, LiOH, and Li2CO3.

[0016] Specifically, optionally, the lithium source powder in step (1) is Li2O.

[0017] Furthermore, the particle size of the lithium source powder in step (1) is in the range of 5 μm to 15 μm.

[0018] Furthermore, in step (1), the molar ratio of the Fe element in the iron oxide powder to the Li element in the lithium source powder is 1:7.0-8.0.

[0019] Furthermore, the inert gas in step (1) is at least one or more of nitrogen, argon, etc.

[0020] Furthermore, the sintering in step (1) refers to pre-sintering at 500-600°C for 5-15h, and then high-temperature sintering at 700-1000°C for 10-28h.

[0021] Furthermore, the pulverizing process in step (1) is performed by using a universal crusher or a jet crusher.

[0022] Furthermore, the universal grinder has a rotation speed of 1000-4000 rpm and a grinding time of 5-20 min.

[0023] Furthermore, the air pressure of the air flow mill is 0.5-0.8 MPa.

[0024] Furthermore, in step (1), a stainless steel screen is used for screening, and the pore size thereof is 250-400 mesh.

[0025] Furthermore, in the step (2), the particle size of the Li5FeO4 lithium supplement additive that wraps the lithium source in the outer layer is 5 μm-15 μm.

[0026] Furthermore, the nickel source in step (2) is one or more of Ni(NO3)2, Ni(OH)2, NiO, and Ni(CH3COO)2.

[0027] Preferably, the nickel source in step (2) is NiO.

[0028] Furthermore, the molar ratio of the Ni element of the nickel source in step (2) to the Li element of the lithium source powder in step (1) is 1:6.0-8.0.

[0029] Furthermore, the inert gas in step (2) is at least one or more of nitrogen, argon, etc.

[0030] Furthermore, the sintering in step (2) refers to pre-sintering at 500-600°C for 7-15h, and then high-temperature sintering at 700-750°C for 15-25h.

[0031] Furthermore, the pulverization process in step (2) is performed using a jet mill.

[0032] Furthermore, the air pressure of the air flow mill is 0.4-0.6 MPa.

[0033] Furthermore, in step (2), a stainless steel screen is used for screening, and the pore size thereof is 250-400 meshes.

[0034] The present invention provides a composite lithium supplement additive Li5FeO4@Li2NiO2 prepared by the above preparation method.

[0035] The present invention provides a composite lithium supplement additive Li5FeO4@Li2NiO2 for use in lithium-ion battery materials.

[0036] Beneficial effects

[0037] 1. Compared with the existing technology, the present invention obtains a composite lithium supplement additive Li5FeO4@Li2NiO2 through step-by-step sintering and temperature control during high-temperature sintering. This composite lithium supplement additive can provide a more excellent charge-discharge specific capacity, with an initial capacity of more than 700mAh / g. It provides a solution for reducing battery capacity loss and improving battery life, and is a lithium supplement additive with market potential.

[0038] 2. Compared with the existing technology, the raw materials used in the present invention are simpler, involving only three types of raw materials: iron oxide, lithium source and nickel source, which are relatively low in price and can reduce the overall process cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the XRD spectrum of the composite lithium supplement additive Li5FeO4@Li2NiO2 prepared in Example 1.

[0040] Figure 2 This is the SEM image of the Li5FeO4 lithium supplement additive with an outer layer wrapped with a lithium source prepared in Example 1.

[0041] Figure 3 This is the SEM image of the composite lithium supplement additive Li5FeO4@Li2NiO2 prepared in Example 1. DETAILED DESCRIPTION

[0042] Source of raw materials

[0043] Iron oxide powder was purchased from Xingxing Electronic New Materials (Wuxi) Co., Ltd. with a particle size of 50-100 nm. Unless otherwise specified, other raw materials used were common commercial products.

[0044] Example 1

[0045] (1) 20 g of iron oxide (Fe2O3) powder and 26.9 g of Li2O powder were mixed to obtain a powdery mixture; the powdery mixture was sintered in a nitrogen atmosphere, first pre-sintered at 500°C for 6 h, then sintered at 850°C for 14 h, and then cooled with the furnace. The sintered and cooled product was crushed using a universal crusher at a speed of 2000 rpm for 5 min, and then passed through a 300-mesh sieve to obtain a Li5FeO4 lithium supplement additive with an outer layer coated with a lithium source;

[0046] (2) 46 g of the prepared Li5FeO4 lithium supplement additive with a lithium source wrapped in an outer layer was mixed evenly with 20 g of NiO to obtain a powdered mixture; the mixture was sintered in a nitrogen atmosphere, first pre-sintered at 550°C for 10 h, then sintered at a high temperature of 700°C for 15 h, and then cooled with the furnace. The sintered and cooled product was then crushed using a jet mill at an air pressure of 0.5 MPa, and then passed through a 300-mesh sieve to obtain a composite lithium supplement additive Li5FeO4@Li2NiO2.

[0047] Example 2

[0048] (1) 20 g of iron oxide (Fe2O3) powder and 27.7 g of Li2O powder were mixed to obtain a powdery mixture; the powdery mixture was sintered in a nitrogen atmosphere, first pre-sintered at 500°C for 6 h, then sintered at 850°C for 14 h, and then cooled with the furnace. The sintered and cooled product was crushed using a universal crusher at a speed of 2000 rpm for 5 min, and then passed through a 300-mesh sieve to obtain a Li5FeO4 lithium supplement additive with an outer layer wrapped with a lithium source;

[0049] (2) 47 g of the prepared Li5FeO4 lithium supplement additive with a lithium source wrapped in an outer layer was mixed evenly with 22 g of NiO to obtain a powdered mixture; the mixture was sintered in a nitrogen atmosphere, first pre-sintered at 550°C for 10 h, then sintered at a high temperature of 700°C for 15 h, and then cooled with the furnace. The sintered and cooled product was then crushed using a jet mill at an air pressure of 0.5 MPa, and then passed through a 300-mesh sieve to obtain a composite lithium supplement additive Li5FeO4@Li2NiO2.

[0050] Example 3

[0051] The difference between this embodiment and embodiment 1 is that the pre-sintering temperature in step (1) is 600° C., but the pre-sintering time remains unchanged, thereby obtaining a composite lithium supplement additive Li 5 FeO 4 @Li 2 NiO 2 .

[0052] Example 4

[0053] The difference between this embodiment and embodiment 1 is that the high-temperature sintering time in step (1) is 28 hours, and the composite lithium supplement additive Li5FeO4@Li2NiO2 is obtained.

[0054] Comparative Example 1

[0055] Referring to the preparation method of Example 1, only the high-temperature sintering temperature in step (2) was changed to 800° C., and the sintering time remained unchanged, to obtain the composite lithium supplement additive Li5FeO4@Li2NiO2.

[0056] Comparative Example 2

[0057] Referring to the preparation method of Example 1, only the high-temperature sintering temperature in step (2) was changed to 600° C., and the sintering time remained unchanged to obtain the composite lithium supplement additive Li 5 FeO 4 @Li 2 NiO 2 .

[0058] Comparative Example 3

[0059] Referring to the preparation method of Example 1, only the Li2O powder in step (1) was replaced with LiOH·H2O powder to obtain the composite lithium supplement additive Li5FeO4@Li2NiO2.

[0060] Comparative Example 4

[0061] Referring to the description in patent CN 119153701 A, 14 g of Li5FeO4 with a particle size of 9 μm, 6 g of Li2NiO2 with a particle size of 11 μm, and 0.1 g of p-phenylenediamine were mixed, then uniformly mixed at 100°C for 1 hour and passed through a 300-mesh sieve to connect the first lithium-rich material to the second lithium-rich material through the functional material, thereby preparing a composite lithium supplement additive Li5FeO4@Li2NiO2.

[0062] The composite lithium supplement additive Li5FeO4@Li2NiO2 prepared in the above examples and comparative examples was tested, and the testing process was as follows:

[0063] (1) XRD test was performed on the prepared composite lithium supplement additive Li5FeO4@Li2NiO2. The test results are as follows: Figure 1 ;

[0064] (2) The prepared Li5FeO4 lithium supplement additive with lithium source wrapped in the outer layer was subjected to SEM test. The test results are as follows Figure 2 ;

[0065] (3) The prepared composite lithium supplement additive Li5FeO4@Li2NiO2 was subjected to SEM test, and the test results are as follows Figure 3 ;

[0066] (4) CR2032 button cells were used to test their electrical performance. The test process was as follows: first, lithium supplement additives Li5FeO4@Li2NiO2: carbon black: PVDF were weighed in a mass ratio of 92:4:4, and then homogenized, coated, baked, cold pressed, cut and assembled into button cells for testing. The test voltage window was 2.5-4.7V, the rate was 0.1C, and the test button cell specific capacity data were shown in Table 1.

[0067] Table 1 Capacity of each embodiment and comparative example

[0068] Capacity (mAh / g, 4.3V) Capacity (mAh / g, 4.5V) Example 1 667.15 705.34 Example 2 665.89 702.59 Example 3 666.56 703.97 Example 4 667.85 704.89 Comparative Example 1 650.56 684.58 Comparative Example 2 652.78 686.54 Comparative Example 3 560.24 598.56 Comparative Example 4 645.18 679.85

[0069] The embodiments provided above are not intended to limit the scope of the present invention, nor are the steps described to limit their execution order. Any obvious improvements to the present invention made by those skilled in the art in combination with existing common knowledge shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a composite lithium supplement additive Li5FeO4@Li2NiO2, characterized in that: The following steps are involved: (1) uniformly mixing iron oxide powder and lithium source powder to obtain a powdery mixture; sintering the powdery mixture in an inert gas atmosphere, and then cooling, crushing, and sieving to obtain a Li5FeO4 lithium supplement additive with an outer layer wrapped with a lithium source; the molar ratio of the Fe element of the iron oxide powder to the Li element of the lithium source powder is 1:7.0-8.0; (2) mixing the lithium-supplementing additive Li5FeO4 coated with a lithium source and a nickel source uniformly to obtain a powdered mixture; sintering the mixture in an inert gas atmosphere, and then cooling, crushing, and sieving to obtain a composite lithium-supplementing additive Li5FeO4@Li2NiO2; the molar ratio of the Ni element of the nickel source to the Li element of the lithium source powder in step (1) is 1:6.0-8.0; sintering refers to pre-sintering at 500-600°C for 7-15h, and then high-temperature sintering at 700-750°C for 15-25h.

2. The preparation method according to claim 1, characterized in that The particle size of the iron oxide powder in step (1) is in the range of 50-100 nm.

3. The preparation method according to claim 1, characterized in that The lithium source powder in step (1) is one or a mixture of Li(NO3)2, Li2O, LiOH, and Li2CO3.

4. The preparation method according to claim 1, characterized in that The particle size of the lithium source powder in step (1) is in the range of 5 μm to 15 μm.

5. The preparation method according to claim 1, characterized in that The sintering in step (1) refers to pre-sintering at 500-600°C for 5-15h, and then high-temperature sintering at 700-1000°C for 10-24h.

6. The preparation method according to claim 1, characterized in that In the step (2), the particle size of the Li5FeO4 lithium supplement additive that wraps the lithium source in the outer layer is 5 μm-15 μm.

7. The preparation method according to claim 1, characterized in that The nickel source in step (2) is one or more of Ni(NO3)2, Ni(OH)2, NiO, and Ni(CH3COO)2.

8. The preparation method according to claim 1, characterized in that The pore size of the sieve in steps (1) and (2) is 250 mesh to 400 mesh.

9. A composite lithium supplement additive Li5FeO4@Li2NiO2, characterized in that: The composite lithium supplement additive Li5FeO4@Li2NiO2 is prepared by the method according to any one of claims 1 to 8.

10. Use of the composite lithium supplement additive Li5FeO4@Li2NiO2 as claimed in claim 9 in lithium-ion battery materials.

Images