A spinel lithium nickel manganese oxide material coated with a double layer of organic matter and its preparation method and application

Abstract

The present invention discloses a spinel lithium nickel manganese oxide material with a double layer of organic coating, as well as its preparation method and application. The material comprises a spinel lithium nickel manganese oxide material core, an inner layer polymer coated on the surface of the core, and an outer layer cross-linked polymer coated on the inner layer polymer; the inner layer polymer is a titanate coupling agent; the outer layer cross-linked polymer is formed by a cross-linking reaction between the titanate coupling agent and a lithiated weakly acidic polymer. The total weight of the inner layer polymer and the outer layer cross-linked polymer is 0.1 to 10% of the weight of the spinel lithium nickel manganese oxide material core, and the mass ratio of the inner layer polymer to the outer layer cross-linked polymer is 1:(0.5 to 3.5). The material of the present invention not only solves the problem that the coating of the lithium nickel manganese oxide material is easy to fall off during circulation, but also has better cycle stability, can effectively inhibit the dissolution of transition metal ions, protect the base material from HF corrosion, and significantly improve the chemical stability, mechanical stability, and structural stability of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a spinel lithium nickel manganese oxide material coated with a double layer of organic matter, and a preparation method and application thereof. Background Art

[0002] Compared to other rechargeable battery systems, lithium-ion secondary batteries offer advantages such as high operating voltage, light weight, compact size, no memory effect, low self-discharge, long cycle life, and high energy density. They are currently widely used in mobile phones, laptops, tablets, electric vehicles, energy storage grids, and other applications. With the rapid development of electric vehicles in recent years, the demand for battery energy density, safety, cost, and environmental friendliness has increased. High-voltage cathodes, as a key means of increasing battery energy density, have become a development trend in liquid lithium-ion batteries and a current research focus. Lithium nickel manganese oxide (LNMO) is a high-voltage cathode material with a voltage platform around 4.7V and a specific energy exceeding 600Wh / kg. Because LNMO is primarily composed of nickel and manganese and contains no cobalt, it is environmentally friendly and relatively inexpensive. Replacing the currently most cost-effective lithium iron phosphate power battery with LNMO could increase the energy density of individual cells and systems by 40% while reducing costs by 30%. Therefore, LNMO has become one of the most promising next-generation high-voltage cathode materials for commercialization.

[0003] However, due to the dissolution of metallic manganese in lithium nickel manganese oxide materials, it migrates to the negative electrode side and destroys the stability of the SEI layer, which can easily lead to problems such as loss of active lithium in the positive electrode material and deterioration of battery cycle performance. One way to effectively prevent the dissolution of metallic manganese is to coat the surface of the lithium nickel manganese oxide material with an electrolyte inert substance to form an artificial barrier. However, traditional coating materials have the problem of easy detachment during the cycle, so the choice of coating agent becomes very important. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a spinel lithium nickel manganese oxide material with a double layer coating of functional organic matter that is ion conductive and surface stable, aiming to overcome the problem that the existing coating technology is easy to fall off on the lithium nickel manganese oxide material.

[0005] The second object of the present invention is to provide a method for preparing the organic double-layer coated spinel lithium nickel manganese oxide material.

[0006] The third object of the present invention is to provide an application of the organic double-layer coated spinel lithium nickel manganese oxide material in lithium ion batteries.

[0007] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a spinel nickel manganese oxide material with a double layer of organic coating, comprising a spinel nickel manganese oxide material core, an inner layer polymer coated on the surface of the inner layer polymer, and an outer layer cross-linked polymer coated on the inner layer polymer; the inner layer polymer is a titanate coupling agent; the outer layer cross-linked polymer is formed by a cross-linking reaction between a titanate coupling agent and a lithiated weakly acidic polymer.

[0009] Preferably, the total weight of the inner layer polymer and the outer layer cross-linked polymer is 0.1-10% of the weight of the spinel nickel manganese oxide material core, more preferably 0.5-2%; the mass ratio of the inner layer polymer to the outer layer cross-linked polymer is 1:(0.5-3.5).

[0010] Preferably, the titanate coupling agent is at least one of NDZ-201, GR-311, and CS-101.

[0011] Preferably, the lithiated weakly acidic polymer is one of lithiated polyacrylic acid and lithiated alginic acid;

[0012] The structural formula of the lithiated polyacrylic acid is:

[0013]

[0014] Among them, 5 <x<25,17<y<48; Preferably 0.2 to 0.4;

[0015] The structural formula of the lithiated alginic acid is:

[0016]

[0017] Among them, 1 <n<10,5<m<15;

[0018] In some embodiments, the chemical formula of the spinel lithium nickel manganese oxide material is LiNi 0.5 Mn 1.5 O4.

[0019] In order to solve the problem that the coating of existing lithium nickel manganese oxide materials is easy to fall off during circulation, the present invention adopts a titanate coupling agent with pyrophosphate and phosphate groups for surface treatment. Due to the chelating effect of pyrophosphate and phosphate on metal manganese ions and nickel ions, and the monoalkoxy produced by the hydrolysis of the titanate coupling agent reacts with the hydroxyl groups on the surface of the positive electrode material to form a coupling, the pyrophosphate group can also decompose to form a phosphate ester group, which combines with the residual moisture on the surface of the positive electrode material to enhance the stability of the transition metal ions. By utilizing the cross-linking effect of the pyrophosphate group and the lithiated weakly acidic polymer, a layer of cross-linked polymer is coated on the outside of the inner layer of polymer to enhance the structural stability of the coating layer. Studies have found that the multi-layer coating structure described in the present invention has better cycle stability, can effectively suppress the solubility of transition metal ions, and protect the lithium nickel manganese oxide material (LiNi 0.5 Mn 1.5 O4) matrix is ​​protected from HF corrosion, significantly improving the chemical stability, mechanical stability and structural stability of the material.

[0020] In a second aspect, the present invention also provides a method for preparing the organic double-layer coated spinel lithium nickel manganese oxide material, comprising: reacting the spinel lithium nickel manganese oxide material with the titanate coupling agent, and pre-coating an inner layer of polymer on the surface of the spinel lithium nickel manganese oxide material; and then coating the inner layer of polymer with an outer layer of cross-linked polymer formed by a cross-linking reaction between the titanate coupling agent and the lithiated weakly acidic polymer, thereby obtaining the organic double-layer coated spinel lithium nickel manganese oxide material.

[0021] Furthermore, the preparation method comprises the following steps:

[0022] 1) In an organic solvent medium, a titanate coupling agent is mixed with a spinel nickel manganese oxide material to react, thereby obtaining a solution A in which an inner layer of polymer is coated on the surface of the spinel nickel manganese oxide material;

[0023] Cross-linking the lithiated weakly acidic polymer with a titanate coupling agent in water or an organic solvent to obtain a solution B;

[0024] 2) mixing solution A and solution B, evaporating the solvent, coating the inner polymer with an outer cross-linked polymer, and then heat-insulating to obtain the organic double-layer coated spinel lithium nickel manganese oxide material.

[0025] Preferably, in step 1), the organic solvent is at least one of isopropyl alcohol, ethanol, and n-butanol; and the mass ratio of the spinel lithium nickel manganese oxide material to the organic solvent is (1-3):1.

[0026] Preferably, in step 1), the cross-linking reaction is carried out at a temperature of 30 to 60° C. and for a time of 1 to 3 hours.

[0027] The lithiated weakly acidic polymer in step 1) can be obtained by reacting a weakly acidic polymer with lithium hydroxide or can be purchased commercially.

[0028] In a third aspect, the present invention further provides an application of the organic double-layer coated spinel lithium nickel manganese oxide material in a lithium ion battery.

[0029] The organic double-layer coated spinel lithium nickel manganese oxide material is used as a positive electrode active material of a lithium ion battery.

[0030] Beneficial effects of the present invention:

[0031] The present invention provides a spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 The surface of the material (O4) is double-coated with an inner polymer and an outer cross-linked polymer composite material. This novel material significantly enhances its bonding with the powder due to the chelation of the inner polymer with the spinel lithium nickel manganese oxide via pyrophosphate groups and transition metals, as well as the coupling between the monoalkoxy groups in the titanate coupling agent and the hydroxyl groups on the surface of the positive electrode material. The outer cross-linked polymer, partially lithiated to form a lithium-conducting layer, effectively improves the ionic conductivity of the spinel lithium nickel manganese oxide material under high-current operating conditions.

[0032] The novel coating concept and structure described in this invention can mitigate the negative effects of moisture erosion in the air, inhibit the dissolution of transition metal ions in the electrolyte, and protect the substrate spinel lithium nickel manganese oxide material from HF corrosion. The organic double-layer coated spinel lithium nickel manganese oxide material described in this invention exhibits enhanced electrochemical properties, good interfacial ion conductivity and stability, and can reduce the resistance to lithium de- and lithium insertion in the cathode material during high-current charge and discharge, demonstrating excellent performance with high capacity, high rate capability, and long cycle life. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is an SEM image of the organic double-layer coated spinel lithium nickel manganese oxide material prepared in Example 1.

[0034] Figure 2 This is a diagram of the electrochemical performance of the organic double-layer coated spinel lithium nickel manganese oxide material prepared in Example 1.

[0035] Figure 3 This is the SEM image of the matrix spinel lithium nickel manganese oxide material in Comparative Example 1.

[0036] Figure 4 This is the electrochemical performance diagram of the matrix spinel lithium nickel manganese oxide material in Comparative Example 1. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0039] Example 1

[0040] Accurately weigh 0.05g NDZ-201, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of isopropanol and stirred for 2 h to obtain solution A; 0.004 g of lithium hydroxide, 0.05 g of polyacrylic acid (molecular weight 3000) and 2 mL of isopropanol were weighed, and then mixed and stirred for 15 min, and then 0.05 g of NDZ-201 was added, and the mixture was sealed and stirred in a water bath at 60 ° C for 2 h to obtain solution B; solution B was then added to solution A, and after continuous stirring for 3 h, the resulting liquid was placed in a 60 ° C oven for 12 h to evaporate the isopropanol and water, and then kept warm at 150 ° C for 1 h to obtain a double-layer organic-coated spinel nickel manganese oxide material with a coating amount of 1.5% and an outer layer organic lithiation amount of 0.25.

[0041] The organic double-layer coated spinel lithium nickel manganese oxide material prepared in this embodiment was examined by scanning electron microscopy. The results are as follows: Figure 1 As shown, there is an obvious continuous polymer film on the surface of the material.

[0042] Electrochemical performance test: The organic double-layer coated spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) material, acetylene black and binder are mixed in a mass ratio of 8:1:1, and N-methylpyrrolidone (NMP) is used as a solvent, and the mixed slurry is obtained by manual grinding. The obtained slurry is coated on an aluminum foil, placed in a vacuum oven at 120°C and dried for 12 hours, and then punched into a disc-shaped electrode with a diameter of 12mm, and the electrode is assembled into a CR2025 button battery in a pure argon glove box. At 25°C, the charge and discharge cut-off voltage is set to 3.5~4.9V for 1C constant current charge and discharge test. After 100 cycles, the organic double-layer coated spinel nickel manganese oxide material still maintains a specific capacity of 131mAh / g, and the capacity retention rate is above 96%. The discharge specific capacity of the material reaches 125mAh / g under 5C high rate charge and discharge conditions, such as Figure 2 shown.

[0043] Example 2

[0044] Accurately weigh 0.05g GR-311, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of isopropanol and stirred for 2 h to obtain solution A; 0.004 g of lithium hydroxide, 0.05 g of polyacrylic acid (molecular weight 3000) and 2 mL of water were weighed, mixed and stirred for 15 min, 0.05 g of GR-311 was added, and the mixture was sealed and stirred in a 60°C water bath for 2 h to obtain solution B; solution B was added to solution A, stirred continuously for 3 h, and then placed in a 60°C oven for 12 h, the isopropanol and water were evaporated, and then kept warm at 150°C for 1 h to obtain an organic double-layer-coated spinel nickel manganese oxide material with a coating amount of 1.5% and an organic outer layer lithiation amount of 0.25.

[0045] The electrochemical performance test was the same as that in Example 1. The battery made of the lithium nickel manganese oxide material had a first cycle capacity of 135.3 mAh / g, a capacity of 129 mAh / g after 100 cycles, and a capacity retention rate of 95.5%.

[0046] Example 3

[0047] Accurately weigh 0.05g CS-101, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of isopropanol and stirred for 2 h to obtain solution A; 0.004 g of lithium hydroxide, 0.05 g of polyacrylic acid (molecular weight 3000) and 2 mL of water were weighed, mixed and stirred for 15 min, 0.05 g of CS-101 was added, and the mixture was sealed and stirred in a 60°C water bath for 2 h to obtain solution B; solution B was added to solution A, stirred continuously for 3 h, and then placed in a 60°C oven for 12 h, the isopropanol and water were evaporated, and then kept at 150°C for 1 h to obtain an organic double-layer-coated spinel nickel manganese oxide material with a coating amount of 1.5% and an organic outer layer lithiation amount of 0.25.

[0048] The electrochemical performance test was the same as that in Example 1. The battery made of the lithium nickel manganese oxide material had a first cycle capacity of 138 mAh / g, a capacity of 130.5 mAh / g after 100 cycles, and a capacity retention rate of 94.5%.

[0049] Example 4

[0050] Accurately weigh 0.05g CS-101, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5O4) was dissolved in 10 mL of isopropanol and stirred for 2 h to obtain solution A; 0.008 g of lithium hydroxide, 0.1 g of polyacrylic acid (molecular weight 3000) and 2 mL of water were weighed, mixed and stirred for 15 min, and then 0.05 g of CS-101 was added. The mixture was sealed and stirred in a water bath at 60°C for 2 h to obtain solution B; solution B was added to solution A, stirred continuously for 3 h, and then placed in a 60°C oven for 12 h, the isopropanol and water were evaporated, and then kept warm at 150°C for 1 h to obtain a double-layer organic-coated spinel nickel manganese oxide material with a coating amount of 2% and an organic outer layer lithiation amount of 0.25.

[0051] The electrochemical performance test was the same as that in Example 1. The battery made of the lithium nickel manganese oxide material had a first cycle capacity of 134 mAh / g, a capacity of 127 mAh / g after 100 cycles, and a capacity retention rate of 94.7%.

[0052] Example 5

[0053] Accurately weigh 0.05g CS-101, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of isopropanol and stirred for 2 h to obtain solution A; 0.0128 g of lithium hydroxide, 0.1 g of polyacrylic acid (molecular weight 3000) and 2 mL of water were weighed, mixed and stirred for 15 min, 0.05 g of CS-101 was added, and the mixture was sealed and stirred in a 60°C water bath for 2 h to obtain solution B; solution B was added to solution A, stirred continuously for 3 h, and then placed in a 60°C oven for 12 h, the isopropanol and water were evaporated, and then kept at 150°C for 1 h to obtain an organic double-layer-coated spinel nickel manganese oxide material with a coating amount of 2% and an organic outer layer lithiation amount of 0.4.

[0054] The electrochemical performance test is the same as that in Example 1. 0.5 Mn 1.5 The battery made of O4) material has a first-cycle capacity of 136.5mAh / g, and after 100 cycles, the capacity is 125mAh / g, with a capacity retention rate of 91.6%.

[0055] Example 6

[0056] Accurately weigh 0.05g CS-101, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5O4) was dissolved in 10 mL of ethanol and stirred for 2 h to obtain solution A; 0.0064 g of lithium hydroxide, 0.1 g of polyacrylic acid (molecular weight 3000) and 2 mL of water were weighed, mixed and stirred for 15 min, 0.05 g of CS-101 was added, and the mixture was sealed and stirred in a 60 ° C water bath for 2 h to obtain solution B; solution B was added to solution A, stirred continuously for 3 h, and then placed in a 60 ° C oven for 12 h, the ethanol and water were evaporated, and then kept at 150 ° C for 1 h to obtain an organic double-layer coated spinel nickel manganese oxide material with a coating amount of 2% and an organic outer layer lithiation amount of 0.2.

[0057] The electrochemical performance test is the same as that in Example 1. 0.5 Mn 1.5 The battery made of O4) material has a first-cycle capacity of 134 mAh / g, and after 100 cycles, the capacity is 123 mAh / g, with a capacity retention rate of 92.1%.

[0058] Example 7

[0059] Accurately weigh 0.05g CS-101, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of n-butanol and stirred for 2 h to obtain solution A; 0.0027 g of lithium hydroxide, 0.1 g of alginic acid (molecular weight 3000) and 2 mL of water were weighed, mixed and stirred for 15 min, 0.05 g of CS-101 was added, and the mixture was sealed and stirred in a 60°C water bath for 2 h to obtain solution B; solution B was added to solution A, stirred continuously for 3 h, and then placed in a 60°C oven for 12 h, the n-butanol and water were evaporated, and then kept at 200°C for 1 h to obtain an organic double-layer-coated spinel nickel manganese oxide material with a coating amount of 2% and an organic outer layer lithiation amount of 0.2.

[0060] The electrochemical performance test is the same as that in Example 1. 0.5 Mn 1.5 The battery made of O4) material has a first-cycle capacity of 129 mAh / g, and after 100 cycles, the capacity is 118 mAh / g, with a capacity retention rate of 91.5%.

[0061] Comparative Example 1

[0062] Matrix spinel lithium nickel manganese oxide material (LiNi 0.5 Mn 1.5 O4), the SEM image after electron microscope scanning is as follows Figure 3 The surface was found to be clean and free of impurities. The electrochemical performance test was the same as in Example 1. The electrochemical performance diagram is shown in FIG. Figure 4 The battery's first-cycle capacity is 128.6 mAh / g. After 100 cycles, the material's discharge capacity is 109 mAh / g, with a capacity retention rate of 85%.

[0063] Comparative Example 2

[0064] Accurately weigh 0.15g CS-101, 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of isopropanol and stirred for 2 hours to obtain a mixed solution. The resulting mixed solution was placed in a 60°C oven for 12 hours, the isopropanol was evaporated, and then kept at 150°C for 1 hour to obtain a single-layer polymer-coated spinel lithium nickel manganese oxide material with a coating weight of 1.5%.

[0065] The electrochemical performance test was the same as that in Example 1. The battery made of the lithium nickel manganese oxide material had a first cycle capacity of 127 mAh / g, a capacity of 114 mAh / g after 100 cycles, and a capacity retention rate of 89.76%.

[0066] Comparative Example 3

[0067] Accurately weigh 0.017g lithium hydroxide, 0.15g polyacrylic acid (molecular weight 3000), 10g spinel lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) was dissolved in 10 mL of isopropanol and stirred for 3 hours to obtain a mixed solution. The resulting mixed solution was placed in a 60°C oven for 12 hours, the isopropanol was evaporated, and then kept at 150°C for 1 hour to obtain a spinel nickel manganese oxide material coated with an outer polymer monolayer with a coating weight of 1.55% and an organic outer layer lithiation weight of 0.35.

[0068] The electrochemical performance test was the same as that in Example 1. The battery made of the lithium nickel manganese oxide material had a first cycle capacity of 128 mAh / g, a capacity of 112 mAh / g after 100 cycles, and a capacity retention rate of 87.5%.

Claims

1. An organic double-layer coated spinel lithium nickel manganese oxide material, characterized in that: The organic double-layer coated spinel lithium nickel manganese oxide material comprises a spinel lithium nickel manganese oxide material core, an inner layer polymer coated on the surface of the core, and an outer layer cross-linked polymer coated on the inner layer polymer; The inner layer polymer is a titanate coupling agent; The outer layer cross-linked polymer is formed by a cross-linking reaction between a titanate coupling agent and a lithiated weakly acidic polymer; The lithiated weakly acidic polymer is one of lithiated polyacrylic acid and lithiated alginic acid; The structural formula of the lithiated polyacrylic acid is: where, 5 < x < 25, 17 < y < 48; degree of lithiation = = 0.1 to 0.6; The structural formula of the lithiated alginic acid is: Among them, 1 < n < 10, 5 < m < 15; lithium content = = 0.1 to 0.

6.

2. The material according to claim 1, characterized in that The total weight of the inner layer polymer and the outer layer cross-linked polymer is 0.1-10% of the weight of the spinel nickel manganese oxide material core; the mass ratio of the inner layer polymer to the outer layer cross-linked polymer is 1:(0.5-3.5).

3. The material according to claim 1, characterized in that The titanate coupling agent is at least one of NDZ-201, GR-311, and CS-101.

4. A method for preparing the organic double-layer coated spinel lithium nickel manganese oxide material according to any one of claims 1 to 3, characterized in that: The preparation method comprises: reacting a spinel lithium nickel manganese oxide material with a titanate coupling agent, pre-coating an inner layer of polymer on the surface of the spinel lithium nickel manganese oxide material; and then coating the inner layer of polymer with an outer layer of cross-linked polymer formed by a cross-linking reaction between the titanate coupling agent and a lithiated weakly acidic polymer, thereby obtaining the spinel lithium nickel manganese oxide material coated with a double layer of organic matter.

5. The preparation method according to claim 4, characterized in that The preparation method comprises the following steps: 1) In an organic solvent medium, a titanate coupling agent is mixed with a spinel nickel manganese oxide material to react, thereby obtaining a solution A in which an inner layer of polymer is coated on the surface of the spinel nickel manganese oxide material; Cross-linking the lithiated weakly acidic polymer with a titanate coupling agent in water or an organic solvent to obtain a solution B; 2) mixing solution A and solution B, evaporating the solvent, coating the inner polymer with an outer cross-linked polymer, and then heat-insulating to obtain the organic double-layer coated spinel lithium nickel manganese oxide material.

6. The preparation method according to claim 5, characterized in that In step 1), the organic solvent is at least one of isopropyl alcohol, ethanol, and n-butanol; and the mass ratio of the spinel lithium nickel manganese oxide material to the organic solvent is (1-3):

1.

7. The preparation method according to claim 5, characterized in that In step 1), the cross-linking reaction temperature is 30-60° C. and the time is 1-3 hours.

8. Use of the organic double-layer coated spinel lithium nickel manganese oxide material according to any one of claims 1 to 3 or the organic double-layer coated spinel lithium nickel manganese oxide material prepared by the preparation method according to any one of claims 5 to 7 in a lithium ion battery.

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