Sulfonic acid-based MXene negative electrode material and preparation method and application thereof

Abstract

The present invention discloses a sulfonic acid group MXene negative electrode material and its preparation method and application. It relates to the technical field of negative electrode materials. The above-mentioned negative electrode material includes a MXene sheet material with a surface modified with a sulfonic acid group, and a columnar structure of Sn is introduced into the structure of the MXene sheet material. 4+ Ion support. The negative electrode material of the present invention can improve the rate performance of the negative electrode material under the combined effect of surface modification of sulfonic acid groups and introduction of columnar Sn4+ ion support. 4+ The ion support structure can adjust the interlayer spacing, further improving ion transport within the battery and effectively reducing the battery's polarization internal resistance. In addition, the surface-modified sulfonic acid groups can provide ideal confined channels, promoting the diffusion of lithium ions within the material, thereby increasing the battery's charge and discharge rates. It can also achieve rapid transport of lithium ions, thereby reducing the occurrence of battery polarization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of negative electrode materials, in particular to a sulfonic acid group MXene negative electrode material and a preparation method and application thereof. BACKGROUND

[0002] With the increasing demand for energy and the rapid development of energy storage technology, the demand for efficient, safe and sustainable battery materials in the energy storage field has become increasingly urgent. In the current fast-charging era, traditional carbon negative electrode materials face a series of challenges. Some carbon negative electrode materials have a small specific surface area, and the speed of lithium ion transport is slow. In large current charging and discharging, lithium is easily deposited on the surface to form lithium dendrites, which may even pierce the separator to cause short circuit and trigger safety problems.

[0003] Under this background, MXene, as a new type of two-dimensional carbon material, has attracted extensive research attention and application prospects. Its unique physical and chemical properties, especially high conductivity and large specific surface area of redox activity, make it have great potential in the field of energy storage. The layered structure of MXene provides an ideal platform for the design of lithium ion batteries. Its porous structure and interlayer gap can provide a confined channel and energy storage space for lithium ions, thereby enhancing the capacity and cycle performance of the battery. More importantly, the rich polar groups on the surface of MXene, such as fluorine (-F), hydroxyl (-OH) and oxygen (-O), enable it to have superior functional group modification capability, further expanding its application potential in battery material modification. However, the existing polarization resistance of lithium ion batteries is still large, which leads to poor cycle performance and affects the service life of lithium ion batteries.

[0004] Recent studies have shown that the introduction of sulfonic acid groups (-SO3H) into lithium ion battery negative electrode materials can create a specific chemical environment to promote the rapid transport of lithium ions. This sulfonic acid modification not only effectively reduces the polarization of lithium batteries, but also significantly improves the cycle life of the battery, thereby improving the reliability and service life of the battery. However, during long-term use, the presence of sulfonic acid groups may cause the capacity of the battery material to gradually decrease and the cycle performance to deteriorate.

[0005] Therefore, there is an urgent need to develop a new type of negative electrode material to more effectively reduce the polarization resistance of lithium batteries and further improve the cycle life. SUMMARY

[0006] The first technical problem to be solved by the present application is:

[0007] To provide a negative electrode material.

[0008] The second technical problem to be solved by the present application is:

[0009] To provide a preparation method of the negative electrode material.

[0010] A third technical problem to be solved by the present application is:

[0011] Application of the negative electrode material.

[0012] To solve the first technical problem, the technical solution adopted by the present application is:

[0013] A negative electrode material, comprising a MXene sheet material with surface-modified sulfonic acid groups, and Sn 4+ ions in a columnar structure introduced into the structure of the MXene sheet material

[0014] According to an embodiment of the present application, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0015] The negative electrode material of the present application, with surface-modified sulfonic acid groups and Sn 4+ ions in a columnar structure, can improve the rate performance of the negative electrode material under the joint action of the two, and the Sn 4+ ion support structure in a columnar structure can adjust the interlayer spacing, further improve the ion transport inside the battery, and effectively reduce the polarization resistance of the battery. In addition, the surface-modified sulfonic acid groups can provide an ideal confined channel to promote the diffusion of lithium ions in the material, thereby improving the charge and discharge rate of the battery, and also realizing the rapid transport of lithium ions, thereby reducing the occurrence of battery polarization.

[0016] To solve the second technical problem, the technical solution adopted by the present application is:

[0017] A method for preparing the negative electrode material, comprising the following steps:

[0018] S1 mixing MXene sheets with cationic surfactants to obtain pre-pillared MXene materials;

[0019] S2 mixing the pre-pillared MXene materials with Sn salts under heating conditions, and then centrifuging and filtering to obtain Sn 4+ pillared MXene sheets;

[0020] S3 mixing the Sn 4+ pillared MXene sheets with a compound containing sulfonic acid groups in a first acidic solution;

[0021] S4 mixing the product of S3 with a reducing agent to undergo sulfonation reaction to obtain the negative electrode material.

[0022] According to an embodiment of the present application, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0023] In step S1, the MXene sheets are mixed with the cationic surfactant, and the cationic surfactant is introduced into the MXene sheets to adjust the interlayer channel spacing of the MXene. Proper adjustment of the channel spacing is helpful for the pillaring of Sn4+ and the introduction of sulfonic acid groups in the subsequent steps. The presence of the cationic surfactant can form a columnar structure on the surface of the MXene sheet, which is helpful for the pillaring of Sn 4+ in the subsequent steps. The pre-pillaring forms some voids between the MXene layers, which is helpful for the introduction of Sn 4+ ions.

[0024] In steps S2-S3, the interlayer of the MXene is treated by using Sn 4+ , so that the interlayer spacing is increased, the bonding force between the layers is correspondingly weakened, and the sheet layers are gradually separated. At this time, it is beneficial to graft the sulfonic acid group functional groups on the surface of the MXene. After the introduction of Sn 4+ ions, the interlayer distance of the MXene material is increased, which is also helpful to improve the transmission rate of lithium ions in the material, which helps to improve the rate performance and cycle life of the lithium ion battery. In addition, the preparation of Sn 4+ pillared MXene sheets is a step to realize surface functionalization, which provides a basis for subsequent modification of sulfonic acid groups, so that sulfonic acid groups can be more easily introduced onto the surface of the MXene, thereby further improving the battery performance.

[0025] The preparation method of the negative electrode material prepared by the method is simple and easy to operate, and can effectively reduce the polarization resistance of the lithium battery and improve the cycle life.

[0026] According to an embodiment of the present application, the preparation method of the MXene sheet comprises: mixing Ti3AlC2 MAX with a second acidic solution, centrifuging to a solution pH greater than 6.0, obtaining a multi-layer Ti3C2Tx, and treating the obtained multi-layer Ti3C2Tx by ultrasonic and centrifugal treatment to obtain the MXene sheet. The second acidic solution is used to exfoliate the Ti3AlC2 into a Ti3C2 MXene material.

[0027] According to an embodiment of the present application, the second acidic solution comprises at least one of a solution of HF, HCl and HClF.

[0028] According to an embodiment of the present application, the cationic surfactant comprises at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, phenyltrimethylammonium chloride, azobisdimethylammonium chloride, cetylphenyltrimethylammonium chloride and hydroxyethyltrimethylammonium chloride.

[0029] According to an embodiment of the present application, in step S2, the system temperature is 100-120℃ under heating conditions.

[0030] According to an embodiment of the present application, the Sn salt comprises at least one of tin chloride, tin nitrate, tin sulfate, tin acetate and tin fluoride.

[0031] According to an embodiment of the present application, the compound containing a sulfonic acid group comprises at least one of sulfanilic acid, sodium sulfonate, benzene sulfonic acid and sulfonamide.

[0032] According to an embodiment of the present application, the reducing agent comprises at least one of sodium nitrite, sodium bisulfite, sodium borohydride, sodium diphosphite and ammonium sulfite.

[0033] According to an embodiment of the present application, in step S4, the product of S3 is mixed with a reducing agent, which functions to introduce a sulfonic acid group to the surface of MXene.

[0034] According to an embodiment of the present application, when the reducing agent is sodium nitrite, the following reaction is specifically involved: first, sodium nitrite (NaNO2) undergoes a reduction reaction in the presence of water (H2O) to generate nitrous acid (HNO2):

[0035] NaNO2+ H2O → HNO2+ NaOH;

[0036] Then, nitrous acid (HNO2) reacts with the sulfanilic acid group on the surface of MXene to initiate a sulfonation reaction, introducing a sulfonic acid group (-SO3H) into the structure of MXene:

[0037] HNO2+ H2N-SO3H → H2N-SO2NH2+ H2O.

[0038] The purpose of this step is to introduce a sulfonic acid group to the surface of MXene through the reducing properties of the reducing agent, achieving surface modification and functionalization. The introduction of this sulfonic acid group can regulate the chemical properties of MXene, thereby reducing the polarization resistance of lithium batteries and improving the cycle life.

[0039] Another aspect of the present application also relates to a lithium ion battery comprising the negative electrode material as described in the above-mentioned embodiment of the first aspect. Since this application adopts all the technical solutions of the above-mentioned negative electrode material, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments.

[0040] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0041] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0042] Figure 1 XRD pattern of the synthesized anode material in Example 1.

[0043] Figure 2 SEM and mapping images of the pillared post-MXene synthesized in Example 1.

[0044] Figure 3 XRD pattern of the synthesized anode material in Example 1.

[0045] Figure 4 Li / Li symmetric cell polarization performance chart of the synthesized anode material in Example 1.

[0046] Figure 5 Li / Cu half-cell coulombic efficiency performance chart of the synthesized anode material in Example 1. DETAILED DESCRIPTION

[0047] In the description of the application, if there is a description of first, second, etc., it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0048] The words "preferably", "more preferably", etc. in the present application refer to embodiments of the present application that can provide certain beneficial effects in certain cases. However, other embodiments can also be preferred in the same or other cases. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not usable, nor is it intended to exclude other embodiments from the scope of the present application.

[0049] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0050] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0051] The reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field unless otherwise specified.

[0052] Example 1

[0053] A negative electrode material comprising MXene sheet material surface modified with sulfonic acid groups, and Sn columnar structure is introduced into the structure of the MXene sheet material 4+ ionically supported.

[0054] The above negative electrode material is prepared, comprising the following steps:

[0055] (1) Preparation of single-layer MXene:

[0056] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49 wt% aqueous HF solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0057] (2) Introduction of Sn between MXene layers 4+ :

[0058] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant CATB solution with a concentration of 0.001 mol / L and stirred at room temperature for 24 h. After centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0059] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration and drying, Sn 4+ pillared MXene sheets were obtained;

[0060] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0061] a: 8 g of sulfanilic acid was added to 30 ml of 1M HCl, stirred in an ice water bath, and then 90 mg of MXene was added to the sulfanilic acid-hydrochloric acid solution and reacted for 30 minutes;

[0062] b: Then 0.70 g of sodium nitrite and 6 ml of H2O were weighed and aerated for 2 hours;

[0063] Using a suction filtration device, the diazonium salt was washed with deionized water until the filtrate was clear, then transferred to a vacuum oven and dried at 50°C under vacuum. The vacuum was maintained in the dark to obtain the negative electrode material.

[0064] Based on the above negative electrode material, a battery was assembled:

[0065] The above negative material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed on the copper foil with a pressure of 10 MPa to form a pole piece. A polypropylene microporous film was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0066] Example 2

[0067] The difference between Example 2 and Example 1 is the concentration of the cationic surfactant CATB.

[0068] A negative electrode material, the above negative electrode material comprising a MXene sheet material with surface-modified sulfonic acid groups, and Sn 4+ ions are introduced into the structure of the MXene sheet material in a columnar structure

[0069] The above negative electrode material is prepared, comprising the following steps:

[0070] (1) Preparation of single-layer MXene:

[0071] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49wt% HF aqueous solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0072] (2) Introduction of Sn 4+ between MXene layers:

[0073] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant CATB with a concentration of 0.5 mol / L and stirred at room temperature for 24 h. After centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0074] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration and drying, a Sn 4+ pillared MXene sheet was obtained;

[0075] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0076] a: 8 g of sulfamic acid was added to 30 ml of 1M HCl, stirred in an ice water bath, and then 90 mg of MXene was added to the sulfamic acid-hydrochloric acid solution and reacted for 30 minutes;

[0077] b: Then 0.70 g of sodium nitrite and 6 ml of H2O were weighed and aerated for 2 hours;

[0078] The diazonium salt was washed with deionized water until the filtrate was clear, then transferred to a vacuum oven at 50°C for vacuum drying, and stored in a vacuum and away from light to obtain the negative electrode material.

[0079] The above negative electrode material was used as the basis to assemble a battery:

[0080] The above negative electrode material, super-P (small particle conductive carbon black), and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed onto the copper foil under a pressure of 10 MPa to form an electrode sheet. A polypropylene microporous film was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0081] Example 3

[0082] The difference between Example 3 and Example 1 is that the concentration of the SnCl4 aqueous solution is different.

[0083] A negative electrode material, the above negative electrode material comprising a MXene sheet material with surface-modified sulfonic acid groups, and Sn 4+ ions supported in a columnar structure in the structure of the MXene sheet material.

[0084] The above negative electrode material was prepared, including the following steps:

[0085] (1) Preparation of single-layer MXene:

[0086] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49wt% HF aqueous solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0087] (2) Introduction of Sn 4+ between MXene layers:

[0088] a: The MXene sheet obtained in (1) was immersed in a cationic surfactant CATB with a concentration of 0.001 mol / L and stirred at room temperature for 24 h. After centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0089] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 10 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration and drying, a Sn 4+ pillared MXene sheet was obtained.

[0090] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0091] a: 8 g of sulfanilic acid was added to 30 ml of 1M HCl, and after stirring in an ice water bath, 90 mg of MXene was added to the sulfanilic acid-hydrochloric acid solution and reacted for 30 minutes;

[0092] b: Then 0.70 g of sodium nitrite and 6 ml of H2O were weighed and aerated for 2 hours;

[0093] Using a suction filtration device, the diazonium salt was washed with deionized water until the filtrate was clear, and then transferred to a vacuum oven for vacuum drying at 50°C. The vacuum dried product was stored in the dark under vacuum to obtain the negative electrode material.

[0094] Based on the above negative electrode material, a battery was assembled:

[0095] The above negative electrode material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed onto the copper foil under a pressure of 10Mpa to form an electrode sheet. A polypropylene microporous membrane was used as a separator, and an electrolyte of 1moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0096] Example 4

[0097] The difference between Example 4 and Example 1 is that the types of cationic surfactants are different.

[0098] A negative electrode material, the above negative electrode material comprising a MXene sheet material with surface-modified sulfonic acid groups, and Sn 4+ ions supported in a columnar structure in the structure of the MXene sheet material.

[0099] The above negative electrode material was prepared, including the following steps:

[0100] (1) Preparation of single-layer MXene:

[0101] Ti3AlC2 MAX, 2.0 g, was immersed in 20 mL of 49 wt% aqueous HF solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multilayer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the undelaminated sediment was removed, and the delaminated MXene sheets were collected in the supernatant by centrifugation at 7500 rpm for 60 min.

[0102] (2) Introducing Sn between MXene layers 4+ :

[0103] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant cetyltrimethylammonium chloride with a concentration of 0.001 mol / L, stirred at room temperature for 24 h, and after centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0104] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L, stirred at 100°C for 24 h, and after centrifugation, water washing, suction filtration and drying, Sn 4+ pillared MXene sheets were obtained;

[0105] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0106] a: 8 g of sulfanilic acid was added to 30 ml of 1M HCl, stirred in an ice water bath, and then 90 mg of MXene was added to the sulfanilic acid-hydrochloric acid solution and reacted for 30 minutes;

[0107] b: Then 0.70 g of sodium nitrite and 6 ml of H2O were weighed and aerated for 2 hours;

[0108] Using a suction filtration device, the diazonium salt was washed with deionized water until the filtrate was clear, then transferred to a vacuum oven for vacuum drying at 50°C, and stored in the dark under vacuum to obtain the negative electrode material.

[0109] Based on the above negative electrode material, a battery was assembled:

[0110] The above negative electrode material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed on the copper foil with a pressure of 10 Mpa to form an electrode sheet. A polypropylene microporous film was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0111] Example 5

[0112] Example 5 differs from Example 1 in that the type of cationic surfactant is different.

[0113] A negative electrode material, the negative electrode material comprising a MXene sheet material having surface-modified sulfonic acid groups, and Sn 4+ ionically supported.

[0114] The negative electrode material is prepared by the following steps:

[0115] (1) Preparation of single-layer MXene:

[0116] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49 wt% aqueous HF solution and magnetically stirred at room temperature for 24 h, then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0117] (2) Introduction of Sn between MXene layers 4+ :

[0118] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant, tetradecylammonium bromide, with a concentration of 0.001 mol / L, and stirred at room temperature for 24 h. After centrifugation, water washing, and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0119] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L, and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration, and drying, a Sn 4+ pillared MXene sheet was obtained;

[0120] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0121] a: 8 g of sulfanilic acid was added to 30 ml of 1M HCl, and after stirring in an ice water bath, 90 mg of MXene was added to the sulfanilic acid-hydrochloric acid solution and reacted for 30 minutes;

[0122] b: Then 0.70 g of sodium nitrite and 6 ml of H2O were weighed and reacted for 2 hours with aeration;

[0123] The dediazo salt was washed with deionized water using a suction filtration device until the filtrate was clear, then transferred to a vacuum oven for vacuum drying at 50°C. The vacuum dried product was stored in the dark under vacuum to obtain the negative electrode material.

[0124] Based on the above negative electrode material, a battery was assembled:

[0125] The above negative electrode material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed on the copper foil with a pressure of 10 MPa to form a pole piece. A polypropylene microporous film was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0126] Example 6

[0127] The difference between Example 6 and Example 1 is that the compound containing a sulfonic acid group in Example 6 is a sulfonamide.

[0128] A negative electrode material, the above negative electrode material includes a MXene sheet material with a surface modified sulfonic acid group, and Sn 4+ ions are introduced into the structure of the MXene sheet material in a columnar structure.

[0129] The above negative electrode material is prepared, including the following steps:

[0130] (1) Preparation of single-layer MXene:

[0131] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49wt% HF aqueous solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0132] (2) Introduction of Sn 4+ between MXene layers:

[0133] a: The MXene sheet obtained in (1) was immersed in a cationic surfactant CATB solution with a concentration of 0.001 mol / L and stirred at room temperature for 24 h. After centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0134] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration and drying, a Sn 4+ pillared MXene sheet was obtained;

[0135] (3) MXene surface modification of sulfonic acid group (-SO3H):

[0136] a: 8 g of sulfonamide is added to 30 ml of 1M HC1, stirred in an ice water bath, then 90 mg of MXene is added to the sulfonamide-hydrochloric acid solution and reacted for 30 minutes;

[0137] b: Then weigh 0.70 g of sodium nitrite and 6 ml of H2O and aerate for 2 hours;

[0138] Use a suction filtration device to wash the diazonium salt with deionized water until the filtrate is clear, then transfer it to a vacuum oven at 50°C and dry it under vacuum. Store it in the dark under vacuum to obtain the negative electrode material.

[0139] Based on the above negative electrode material, assemble the battery:

[0140] Weigh the above negative electrode material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) in a mass ratio of 8:1:1, use deionized water as the solvent, stir and evenly coat on the copper foil, dry and then use a pressure of 10Mpa to press the active material on the copper foil to make the electrode sheet. Use a polypropylene microporous membrane as the separator, electrolyte as 1moL / L LiPF6 / EC:DEC (1:1), and assemble into a 2032 lithium ion button cell in an Ar atmosphere.

[0141] Example 7

[0142] The difference between Example 7 and Example 1 is that the compound containing a sulfonic acid group in Example 7 is sodium sulfonate.

[0143] A negative electrode material, the above negative electrode material includes MXene sheet material surface modified with a sulfonic acid group, and the structure of the MXene sheet material introduces Sn 4+ ion support.

[0144] The above negative electrode material is prepared, including the following steps:

[0145] (1) Preparation of single-layer MXene:

[0146] 2.0 g of Ti3AlC2 MAX is immersed in 20 mL of 49wt% HF aqueous solution, magnetically stirred at room temperature for 24 h, then the acidic mixture is washed with deionized water and centrifuged until the solution pH is greater than 6.0. The obtained multi-layer Ti3C2Tx is ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that has not been delaminated is removed, and the delaminated MXene sheet is collected in the supernatant by centrifugation at 7500 rpm for 60 min.

[0147] (2) Introduction of Sn between MXene layers 4+ :

[0148] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant CATB with a concentration of 0.001 mol / L at room temperature for 24 h. After centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0149] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration and drying, Sn 4+ pillared MXene sheets were obtained.

[0150] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0151] a: 8 g of sodium sulfonate was added to 30 ml of 1M HCl, and after stirring in an ice water bath, 90 mg of MXene was added to the sodium sulfonate-hydrochloric acid solution and reacted for 30 minutes;

[0152] b: Then 0.70 g of sodium nitrite and 6 ml of H2O were weighed and aerated for 2 hours;

[0153] Using a suction filtration device, the diazonium salt was washed with deionized water until the filtrate was clear, then transferred to a vacuum oven at 50°C for vacuum drying. The vacuum was maintained in the dark to obtain the negative electrode material.

[0154] Based on the above negative electrode material, a battery was assembled:

[0155] The above negative electrode material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed onto the copper foil using a pressure of 10Mpa to form an electrode sheet. A polypropylene microporous membrane was used as a separator, and an electrolyte of 1moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0156] Example 8

[0157] The difference between Example 8 and Example 1 is the reducing agent.

[0158] A negative electrode material, the above negative electrode material comprising MXene sheet material with surface modified sulfonic acid groups, and Sn 4+ ions supported by a columnar structure are introduced into the structure of the MXene sheet material.

[0159] The above negative electrode material is prepared, comprising the following steps:

[0160] (1) Preparation of single-layer MXene:

[0161] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49 wt% aqueous HF solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multilayer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0162] (2) Introducing Sn between MXene layers 4+ :

[0163] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant CATB with a concentration of 0.001 mol / L and stirred at room temperature for 24 h. After centrifugation, water washing and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0164] b: The pre-pillared Ti3C2 MXene material was added to an aqueous SnCl4 solution with a concentration of 0.05 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration and drying, Sn 4+ pillared MXene sheets were obtained;

[0165] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0166] a: 8 g of sulfanilic acid was added to 30 ml of 1M HCl, stirred in an ice water bath, and then 90 mg of MXene was added to the sulfanilic acid-hydrochloric acid solution and reacted for 30 minutes;

[0167] b: Then 0.59 g of sodium bisulfite and 6 ml of H2O were weighed and aerated for 2 hours;

[0168] The diazonium salt was washed with deionized water until the filtrate was clear using a suction filtration device, and then transferred to a vacuum oven for vacuum drying at 50°C. The vacuum was maintained in the dark to obtain the negative electrode material.

[0169] Based on the above negative electrode material, a battery was assembled:

[0170] The above negative electrode material, super-P (small particle conductive carbon black) and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed onto the copper foil using a pressure of 10Mpa to form an electrode sheet. A polypropylene microporous membrane was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0171] Example 9

[0172] Example 9 differs from Example 1 in that the reducing agent is different.

[0173] A negative electrode material, the negative electrode material comprising a MXene sheet material with surface-modified sulfonic acid groups, and Sn 4+ ionically supported.

[0174] The negative electrode material is prepared, comprising the following steps:

[0175] (1) Preparation of single-layer MXene:

[0176] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49 wt% aqueous HF solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2Tx was ultrasonically dispersed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the sediment that did not delaminate was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0177] (2) Introduction of Sn between MXene layers 4+ :

[0178] a: The MXene sheets obtained in (1) were immersed in a cationic surfactant CATB solution with a concentration of 0.001 mol / L and stirred at room temperature for 24 h. After centrifugation, water washing, and drying, a pre-pillared Ti3C2 MXene material was obtained;

[0179] b: The pre-pillared Ti3C2 MXene material was added to a SnCl4 aqueous solution with a concentration of 0.05 mol / L and stirred at 100°C for 24 h. After centrifugation, water washing, suction filtration, and drying, Sn 4+ pillared MXene sheets were obtained;

[0180] (3) Surface modification of MXene with sulfonic acid groups (-SO3H):

[0181] a: 8 g of sulfanilic acid was added to 30 ml of 1M HCl, stirred in an ice water bath, and then 90 mg of MXene was added to the sulfanilic acid-hydrochloric acid solution and reacted for 30 minutes;

[0182] b: Then 0.30 g of sodium borohydride and 6 ml of H2O were weighed and the reaction was carried out for 2 hours with aeration;

[0183] The diazonium salt was washed with deionized water using a suction filtration device until the filtrate was clear, then transferred to a vacuum oven for vacuum drying at 50°C. The vacuum dried product was stored in the dark under vacuum to obtain the negative electrode material.

[0184] A battery was assembled based on the above negative electrode material.

[0185] The above negative electrode material, super-P (small particle conductive carbon black), and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, respectively, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed on the copper foil using a pressure of 10 MPa to make an electrode sheet. A polypropylene microporous film was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0186] Comparative Example 1

[0187] A negative electrode material, the above negative electrode material comprising a single-layer MXene sheet material prepared by a conventional method.

[0188] The above negative electrode material was prepared, including the following steps:

[0189] Preparation of single-layer MXene:

[0190] 2.0 g of Ti3AlC2 MAX was immersed in 20 mL of 49 wt% aqueous HF solution, magnetically stirred at room temperature for 24 h, and then the acidic mixture was washed with deionized water and centrifuged until the solution pH was greater than 6.0. The obtained multi-layer Ti3C2T x Ultrasonic dispersion in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the undelaminated sediment was removed, and the delaminated MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0191] After transfer to a vacuum oven, vacuum drying was performed at 50°C, and the product was stored in the dark under vacuum to obtain the negative electrode material.

[0192] A battery was assembled based on the above negative electrode material.

[0193] The above negative electrode material, super-P (small particle conductive carbon black), and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, respectively, deionized water was used as the solvent, and after stirring, they were uniformly coated on a copper foil. After drying, the active material was pressed on the copper foil using a pressure of 10 MPa to make an electrode sheet. A polypropylene microporous film was used as a separator, and an electrolyte of 1 moL / L LiPF6 / EC:DEC (1:1) was used to assemble a 2032 lithium ion button cell in an Ar atmosphere.

[0194] Comparative Example 2

[0195] A negative electrode material, the above negative electrode material comprising a single-layer MXene sheet material prepared by a conventional method.

[0196] The preparation of the above-mentioned negative electrode material comprises the following steps:

[0197] Preparation of single-layer MXene:

[0198] Weigh 2g of LiF and add it to 40mL of 9M HCl solution, then slowly add 2g of Ti3AlC2-MAX phase, stir at 35℃ and 350rpm / min for 24 hours; then wash the acidic mixture with deionized water and centrifuge until the solution pH is greater than 6.0. x Ultrasonic dispersion was performed in deionized water for 1 h. After centrifugation at 1500 rpm for 60 min, the unstratified sediment was removed and the stratified MXene sheets in the supernatant were collected by centrifugation at 7500 rpm for 60 min.

[0199] The product was then transferred to a vacuum oven at 50° C. for vacuum drying, evacuated and stored away from light to obtain the negative electrode material.

[0200] Based on the above negative electrode materials, assemble the battery:

[0201] The aforementioned negative electrode materials, super-P (small particle conductive carbon black), and CMC (carboxymethyl cellulose) were weighed in a mass ratio of 8:1:1, stirred, and evenly coated onto copper foil using deionized water as the solvent. After drying, the active material was pressed onto the copper foil using a pressure of 10 MPa to form a pole piece. A 2032 lithium-ion button cell was assembled in an Ar atmosphere using a polypropylene microporous film as the separator and a 1 mol / L LiPF6 / EC:DEC (1:1) electrolyte.

[0202] Performance testing:

[0203] The negative electrode material synthesized in Example 1 was subjected to XRD test, and the results were as follows: Figure 1 As shown, Figure 1 Intensity refers to strength. Figure 1 The XRD analysis results showed that the peak position shifted, confirming that Sn 4+ After successful insertion into the interlayer of MXene, the increase in the interlayer spacing weakens the bonding force between the sheets, and the sheets gradually separate. This is conducive to grafting sulfonic acid functional groups on the surface of MXene for aromatic diazonium salt modification.

[0204] The pillared MXene synthesized in Example 1 was subjected to SEM and mapping tests, wherein: Figure 2 (a) is the SEM image, Figure 2 (b) is the mapping diagram. The results of the SEM and mapping diagrams above show that the MXene after etching has an obvious accordion structure, which further proves that Sn 4+ Successfully introduced into MXene.

[0205] The XRD test of the negative electrode material synthesized in Example 1 is an infrared spectrum of Ti3C2 before and after diazonium salt surface modification. The test results are as follows: Figure 3 shown. Figure 3 In the equation, Wave number is the wave number and Transmittance is the transmittance. Figure 3 The presence of -F, -O, and -OH surface functional groups is clearly shown (1640, 1616, and 1134 cm -1 In the FTIR spectrum of the negative electrode material, the -SO3H group (1108 and 1160 cm -1 )The characteristic absorption band of OSO is extended, confirming that -SO3H is successfully introduced into Ti3C2.

[0206] Figure 4 This is a diagram of the Li / Li symmetric battery polarization performance of the negative electrode material synthesized in Example 1. Figure 4 In the table, Time is time and Voltage is voltage. Figure 4 The Li / Li polarization performance diagram shows that the Ti3C2–SO3H-Li symmetric battery has a high -2 、1mAhcm -2 The sample can be stably cycled for at least 1500 hours under the charge and discharge conditions. On the other hand, at the same current density, the control sample shows a gradual increase in polarization voltage after 1000 hours due to the accumulation of interfacial impedance.

[0207] Figure 5 This is a performance diagram of the Li / Cu half-cell coulombic efficiency of the negative electrode material synthesized in Example 1. Figure 5 In the equation, CycleNumber is the number of cycles, and Coulombic Efficiency is the Coulombic efficiency. Figure 5 The Li / Cu half-cell coulombic efficiency diagram in the figure shows that compared with pure Cu, the negative electrode material of the present invention has a higher and more stable coulombic efficiency and a longer service life due to the more uniform lithium deposition. This is due to the rich sulfonate (-SO 3- ) provides an ideal specific chemical environment for the confined channel, and through the synergistic effect of the confined channel and the chemical environment, the rapid transport of lithium ions is achieved.

[0208] The results of Examples 2 to 9 are similar to those of Example 1 and are not shown one by one to avoid redundancy.

[0209] The above are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A negative electrode material, characterized by: The negative electrode material comprises a MXene sheet material with surface modified sulfonic acid groups, and a columnar structure of Sn is introduced into the structure of the MXene sheet material 4+ Ionically supported; The preparation method of the negative electrode material comprises the following steps: S1 mixing MXene sheets with a cationic surfactant, centrifuging, water washing, and drying to obtain a pre-pillared MXene material; S2 mixing the pre-pillared MXene material and the Sn salt under heating conditions, centrifuging and filtering to obtain Sn 4+ pillared MXene sheets; S3 Under the first acidic solution, mix Sn 4+ Pillared MXene sheets with compounds containing sulfonic acid groups; S4 mixing the product of S3 with a reducing agent, and performing a sulfonation reaction to obtain a negative electrode material.

2. The negative electrode material of claim 1, wherein: In the negative electrode material, Sn 4+ The mass percentage of the ion is 5-6%.

3. A method of producing a negative electrode material as claimed in claim 1 or 2, characterized in that: comprises the following steps: S1 mixing MXene sheets with a cationic surfactant, centrifuging, water washing, and drying to obtain a pre-pillared MXene material; S2 mixing the pre-pillared MXene material and the Sn salt under heating conditions, centrifuging and filtering to obtain Sn 4+ pillared MXene sheets; S3 Under the first acidic solution, mix Sn 4+ Pillared MXene sheets with compounds containing sulfonic acid groups; S4 mixing the product of S3 with a reducing agent, and performing a sulfonation reaction to obtain a negative electrode material.

4. The method of claim 3, wherein: The preparation method of the MXene sheet comprises: mixing Ti3AlC2MAX with a second acidic solution, centrifuging to a solution pH greater than 6.0, and obtaining a multilayer Ti3C2T x , and obtaining the MXene sheet through ultrasonic and centrifugal treatment.

5. The method of claim 3, wherein: In step S2, the system temperature is 100-120℃ under heating.

6. The method of claim 3, wherein: The Sn salt comprises at least one of tin chloride, tin nitrate, tin sulfate, tin acetate, and tin fluoride.

7. The method of claim 3, wherein: The compound containing a sulfonic acid group comprises at least one of sulfanilic acid, sodium sulfonate, benzene sulfonic acid, and sulfonamide.

8. The method of claim 3, wherein: The reducing agent comprises at least one of sodium nitrite, sodium bisulfite, sodium borohydride, sodium diphosphite, and ammonium sulfite.

9. A lithium-ion battery, characterized by: comprises the negative electrode material of claim 1 or 2.

Images