A porous MXene-coated lithium-ion battery cathode material and preparation method thereof

Abstract

The present invention discloses a porous MXene-coated lithium-ion battery positive electrode material and a preparation method thereof, comprising a lithium battery positive electrode material and a porous MXene coating layer coated thereon. The preparation method first prepares a cellulose-supported porous MXene dispersion coating liquid. Since the surface of the MXene material contains a large number of oxygen-containing functional groups, the dispersion coating liquid has a negative charge property; secondly, the positive electrode material is cationically coated and the surface of the positive electrode material is treated with a cationic surfactant to give the positive electrode material a certain positive charge property; finally, the positive and negative charges are adsorbed to cause the MXene coating material and the positive electrode material to self-assemble, thereby realizing the preparation of the porous MXene nanosheet-coated positive electrode material.

Description

Technical Field

[0001] The present application relates to the technical field of lithium battery material preparation, and in particular to a porous MXene-coated lithium-ion battery positive electrode material and a preparation method thereof. Background Art

[0002] Against the backdrop of global warming and the increasing depletion of fossil energy, the development and utilization of renewable energy is receiving increasing attention from the international community, and vigorously developing renewable energy has become a consensus among countries around the world. Lithium-ion batteries have experienced rapid development in recent years. Lithium-ion batteries are rechargeable batteries that achieve the mutual conversion between chemical energy and electrical energy through the intercalation and deintercalation of lithium ions between the positive and negative electrodes. In the composition of lithium-ion batteries, electrode materials are an important factor in determining their safety performance, electrochemical performance, and future development direction. In currently commercialized lithium-ion batteries, the main cathode materials used are lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials. However, these electrode materials all have problems with low conductivity and surface activity during use, which affects the overall performance of lithium batteries. Summary of the Invention

[0003] The purpose of the embodiments of the present application is to provide a porous MXene-coated lithium-ion battery positive electrode material and a preparation method thereof. Taking advantage of the high specific surface area, high electrical conductivity, low ion diffusion resistance and other characteristics of MXene materials, the positive electrode material prepared by the present invention has better conductivity, faster lithium ion diffusion rate and better rate performance, thereby improving the coulombic efficiency of lithium-ion batteries and improving high-current rapid charge and discharge performance. At the same time, the porous MXene of the present invention is supported by cellulose cross-linking, has a large porosity and high mechanical properties, can solve the problem of unfriendly interface between electrode materials and solid electrolytes through mechanical compaction, and can also effectively alleviate the volume expansion of electrode active substances, thereby making solid-state lithium batteries possible.

[0004] According to a first aspect of an embodiment of the present application, a porous MXene-coated lithium-ion battery positive electrode material is provided, comprising: a lithium battery positive electrode material and a porous MXene coating layer coated thereon.

[0005] Preferably, the lithium battery positive electrode material is selected from one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium iron phosphate, and ternary materials; and the porous MXene coating layer is formed by cross-linking porous MXene nanosheets and cellulose.

[0006] According to a second aspect of an embodiment of the present application, a method for preparing a porous MXene-coated lithium-ion battery positive electrode material is provided, comprising:

[0007] S1: Preparation of cellulose-supported porous MXene dispersion coating solution, including:

[0008] S11: Preparation of porous MXene nanosheet solution: MXene nanosheets are stirred and dispersed in a hydrogen peroxide solution, stirred and etched, and the resulting solution is centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution;

[0009] S12: Preparation of cellulose dispersion: adding cellulose raw material to deionized water, crushing and stirring to fully and evenly disperse it to obtain a cellulose dispersion;

[0010] S13: adding the porous MXene nanosheet solution to the cellulose dispersion and stirring to obtain a cellulose-supported porous MXene dispersion coating solution;

[0011] S2: Cationic coating of the positive electrode material: The positive electrode material and the cationic surfactant are dispersed in a polar solvent solution, heated and stirred to completely volatilize the solution, and the dried solid powder is ground to obtain a positive electrode material with a surface coated with cations;

[0012] S3: The cellulose-supported porous MXene dispersion coating liquid and the surface-coated cation positive electrode material are fully mixed and stirred, centrifuged and washed with water, and freeze-dried to obtain a lithium-ion battery positive electrode material coated with porous MXene nanosheets.

[0013] In the above preparation method, the first step is to prepare a cellulose-supported porous MXene dispersion coating liquid. Since the surface of the MXene material contains a large number of oxygen-containing functional groups, the dispersion coating liquid has a negative charge property; secondly, the positive electrode material is cationically coated and the surface of the positive electrode material is treated with a cationic surfactant to give the positive electrode material a certain positive charge property; finally, the positive and negative charges are adsorbed to allow the MXene coating material and the positive electrode material to self-assemble, thereby realizing the preparation of porous MXene nanosheet-coated positive electrode material.

[0014] Preferably, the MXene nanosheets are preferably Ti3C2T x .

[0015] Preferably, the mass ratio of the MXene nanosheets to the H2O2 solution is 0.1 to 1, and the mass concentration of the H2O2 solution is 0.01% to 0.1%.

[0016] Preferably, the etching temperature is 20-80° C., and the etching time is 10-100 min.

[0017] Preferably, the cellulose comprises one or more of bacterial cellulose, nanocellulose, microcellulose, and oxidized cellulose, preferably bacterial cellulose.

[0018] Preferably, the mass ratio of the MXene nanosheets to cellulose is 20:1 to 1:1.

[0019] Preferably, the mass percentage of cellulose in the cellulose dispersion is 0.5-4%.

[0020] Preferably, the cationic surfactant is selected from one or more mixtures of silane coupling agent KH550, hexadecyltrimethylammonium bromide (CTAB), and polydiallyldimethylammonium chloride (PDDA), and the mass ratio of the positive electrode material to the cationic surfactant is 1:0.5-2.

[0021] Preferably, the polar solvent is one or a mixture of deionized water and anhydrous ethanol, and the mass ratio of the polar solvent to the positive electrode material is 200:1.

[0022] Preferably, the mass ratio of the MXene nanosheets to the positive electrode material is 1:5-20.

[0023] The technical solutions provided by the embodiments of the present application may have the following beneficial effects:

[0024] It can be seen from the above embodiments that compared with commercial positive electrode materials, the porous MXene-coated lithium-ion battery positive electrode material of the present invention has better conductivity, faster lithium ion diffusion rate and better rate performance, thereby improving the coulombic efficiency of lithium-ion batteries, improving large current fast charging and discharging performance, and realizing application in high-power / fast-charging lithium-ion battery products.

[0025] The porous MXene layer in the porous MXene-coated lithium-ion battery positive electrode material of the present invention is supported by cellulose cross-linking, has a large porosity and high mechanical properties, can solve the problem of unfriendly interface between electrode materials and solid electrolytes through mechanical compaction, and can also effectively alleviate the volume expansion of electrode active substances, thereby making solid-state lithium batteries possible.

[0026] The preparation method of the present invention has simple process, easy control, low cost, and is green and pollution-free from the use of raw materials to the preparation process, which is conducive to large-scale industrial production.

[0027] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. DETAILED DESCRIPTION

[0028] Here, exemplary embodiments will be described in detail. Example 1:

[0029] A method for preparing a porous MXene-coated lithium-ion battery positive electrode material comprises the following steps:

[0030] S1: Preparation of cellulose-supported porous MXene dispersion coating solution, the steps are as follows:

[0031] S11. Preparation of porous MXene nanosheet solution: 20 parts by weight of Ti3C2T x The nanosheets were stirred and dispersed into 200 parts by weight of a 0.01% hydrogen peroxide (H2O2) solution, stirred and etched at 20°C for 10 minutes, and then the reacted solution was centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution.

[0032] S12. Preparation of cellulose dispersion: Add 200 parts by weight of deionized water to 1 part by weight of bacterial cellulose raw material, and use a high-speed stirrer to crush and stir at a speed of 15,000 rpm to fully and evenly disperse the raw material to obtain a bacterial cellulose dispersion.

[0033] S13. Preparation of cellulose-supported porous MXene dispersion coating liquid: The porous MXene nanosheet solution prepared in S11 is added to the bacterial cellulose dispersion liquid prepared in S12, and the mixture is stirred thoroughly to obtain the bacterial cellulose-supported porous MXene dispersion coating liquid.

[0034] S2: Cationic coating of the positive electrode material: 100 parts by weight of NCA811 ternary electrode material and 50 parts by weight of CTAB (cetyltrimethylammonium bromide) are dispersed in 2000 parts by weight of anhydrous ethanol solution, heated and stirred to completely evaporate the solution, and the dried solid powder is ground for later use to obtain the CTAB-coated NCA811 ternary electrode material.

[0035] S3: The cellulose-supported porous MXene dispersion coating liquid prepared in S1 and the CTAB-coated NCA811 ternary electrode material obtained in S2 are thoroughly mixed and stirred, centrifuged and washed three times with water, and freeze-dried. The dried product is the NCA811 ternary electrode material coated with porous MXene nanosheets. Example 2:

[0036] A method for preparing a porous MXene-coated lithium-ion battery positive electrode material comprises the following steps:

[0037] S1: Preparation of cellulose-supported porous MXene dispersion coating solution, the steps are as follows:

[0038] S11. Preparation of porous MXene nanosheet solution: 10 parts by weight of Ti3C2T x The nanosheets were stirred and dispersed in 20 parts by weight of a 0.05% hydrogen peroxide (H2O2) solution, stirred and etched at 50°C for 50 minutes, and then the reacted solution was centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution.

[0039] S12. Preparation of cellulose dispersion: Add 50 parts by weight of deionized water to 1 part by weight of bacterial cellulose raw material, and use a high-speed stirrer to crush and stir at a speed of 20,000 rpm to fully and evenly disperse the raw material to obtain a bacterial cellulose dispersion.

[0040] S13. Preparation of cellulose-supported porous MXene dispersion coating liquid: The porous MXene nanosheet solution prepared in S11 is added to the bacterial cellulose dispersion liquid prepared in S12, and the mixture is stirred thoroughly to obtain the bacterial cellulose-supported porous MXene dispersion coating liquid.

[0041] S2: Cationic coating of the positive electrode material: 100 parts by weight of NCM523 ternary electrode material and 100 parts by weight of PDDA (polydimethyldiallyl ammonium chloride) are dispersed in 2000 parts by weight of anhydrous ethanol solution, heated and stirred to completely evaporate the solution, and the dried solid powder is ground for later use to obtain the PDDA-coated NCM523 ternary electrode material.

[0042] S3: The cellulose-supported porous MXene dispersion coating liquid prepared in S1 and the PDDA-coated NCM523 ternary electrode material obtained in S2 are fully mixed and stirred, centrifuged and washed three times with water, and freeze-dried. The dried product is the NCM523 ternary electrode material coated with porous MXene nanosheets. Example 3:

[0043] A method for preparing a porous MXene-coated lithium-ion battery positive electrode material comprises the following steps:

[0044] S1: Preparation of cellulose-supported porous MXene dispersion coating solution, the steps are as follows:

[0045] S11. Preparation of porous MXene nanosheet solution: 1 part by weight of Ti3C2T x The nanosheets were stirred and dispersed into 1 part by weight of a 0.1% hydrogen peroxide (H2O2) solution, stirred and etched at 80°C for 100 minutes, and then the reacted solution was centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution.

[0046] S12. Preparation of cellulose dispersion: dilute 1 part by weight of bacterial cellulose raw material with 25 parts by weight of water, and use a high-speed stirrer to crush and stir at a speed of 30,000 rpm to fully and evenly disperse the raw material to obtain a bacterial cellulose dispersion.

[0047] S13. Preparation of cellulose-supported porous MXene dispersion coating liquid: The porous MXene nanosheet solution prepared in S11 is added to the bacterial cellulose dispersion liquid prepared in S12, and the mixture is stirred thoroughly to obtain the bacterial cellulose-supported porous MXene dispersion coating liquid.

[0048] S2: Cationic coating of the positive electrode material: 20 parts by weight of lithium iron phosphate material and 40 parts by weight of silane coupling agent KH550 are dispersed in 400 parts by weight of anhydrous ethanol solution, heated and stirred to completely evaporate the solution, and the dried solid powder is ground for later use to obtain a silane coupling agent-coated lithium iron phosphate positive electrode material.

[0049] S3: The cellulose-supported porous MXene dispersion coating liquid prepared in S1 and the silane coupling agent-coated lithium iron phosphate positive electrode material obtained in S2 are fully mixed and stirred, centrifuged and washed three times with water, and freeze-dried. The dried product is the lithium iron phosphate positive electrode material coated with porous MXene nanosheets.

[0050] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the contents disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of the present application and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered merely as exemplary, and the true scope and spirit of the present application are indicated by the claims.

[0051] It should be understood that the present application is not limited to the precise structure described above and that various modifications and changes can be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for preparing a porous MXene-coated lithium-ion battery cathode material, characterized in that: include: S1: Preparation of cellulose-supported porous MXene dispersion coating solution, including: S11: Preparation of porous MXene nanosheet solution: MXene nanosheets are stirred and dispersed in a hydrogen peroxide solution, stirred and etched, and the resulting solution is centrifuged and washed, and ultrasonically dispersed to obtain a porous MXene nanosheet solution; S12: Preparation of cellulose dispersion: adding cellulose raw material to deionized water, crushing and stirring to fully and evenly disperse it to obtain a cellulose dispersion; S13: adding the porous MXene nanosheet solution to the cellulose dispersion and stirring to obtain a cellulose-supported porous MXene dispersion coating solution; S2: Cationic coating of the positive electrode material: The positive electrode material and the cationic surfactant are dispersed in a polar solvent solution, heated and stirred to completely volatilize the solution, and the dried solid powder is ground to obtain a positive electrode material with a surface coated with cations; S3: The cellulose-supported porous MXene dispersion coating liquid and the surface-coated cation positive electrode material are fully mixed and stirred, centrifuged and washed with water, and freeze-dried to obtain a lithium-ion battery positive electrode material coated with porous MXene nanosheets.

2. The preparation method according to claim 1, characterized in that The MXene nanosheets are Ti3C2T x .

3. The preparation method according to claim 1, characterized in that The mass ratio of the MXene nanosheets to the H2O2 solution is 0.1-1, and the mass concentration of the H2O2 solution is 0.01%-0.1%.

4. The preparation method according to claim 1, characterized in that The etching temperature is 20-80° C., and the etching time is 10-100 minutes.

5. The preparation method according to claim 1, characterized in that The cellulose includes one or more of bacterial cellulose, nanocellulose, microcellulose, and oxidized cellulose.

6. The preparation method according to claim 5, characterized in that The cellulose is bacterial cellulose.

7. The preparation method according to claim 1, characterized in that The mass ratio of the MXene nanosheets to the cellulose is 20:1 to 1:

1.

8. The preparation method according to claim 4, characterized in that The mass percentage of cellulose in the cellulose dispersion is 0.5-4%.

9. The preparation method according to claim 1, characterized in that The cationic surfactant is selected from one or more mixtures of silane coupling agent KH550, hexadecyltrimethylammonium bromide (CTAB), and polydiallyldimethylammonium chloride (PDDA), and the mass ratio of the positive electrode material to the cationic surfactant is 1:0.5-2.

10. The preparation method according to claim 1, characterized in that The polar solvent is one of deionized water and anhydrous ethanol or a mixture of the two, and the mass ratio of the polar solvent to the positive electrode material is 200:

1.

11. The preparation method according to claim 1, characterized in that The mass ratio of the MXene nanosheets to the positive electrode material is 1:5-20.