An in-situ sulfurized Ni9S8 nanorod / MXene composite anode material and its preparation method and application

Abstract

The present invention discloses an in-situ sulfurized Ni9S8 nanorod / MXene composite anode material, its preparation method and application, belonging to the technical field of electrode materials. The preparation method includes the following steps: mixing a nickel-containing compound with an aqueous solution of few-layer MXene, reacting under ultrasonic conditions by means of electrostatic adsorption to obtain an intermediate product; dispersing the intermediate product and a sulfurizing agent in an organic solvent for in-situ sulfurization, and after the reaction is completed, washing and annealing the obtained product to obtain the Ni9S8 nanorod / MXene composite anode material. The present invention also discloses the composite anode material prepared by the above preparation method and its application in electrode materials. In the composite anode material provided by the present invention, the MXene nanosheets and Ni9S8 nanorods cooperate with each other, showing good reversibility and cycle stability. Moreover, the preparation method provided by the present invention is simple and environmentally friendly, which is conducive to popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and particularly relates to an in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material and its preparation method and application. Background Art

[0002] The overuse of fossil fuels has caused a global energy crisis and also exacerbated environmental pollution. Seeking clean energy to replace fossil fuels and reduce dependence on fossil fuels has become an irresistible trend. As a new type of clean energy, lithium-ion batteries (LIBs) are widely used in people's daily lives due to their excellent comprehensive performance. However, due to the limited lithium resources, the price of lithium-ion batteries remains high, which prompts people to search for alternative batteries from abundant elements in nature. Sodium is abundant in nature, and sodium and lithium belong to the same main group, with a working principle similar to that of lithium-ion batteries. Therefore, sodium-ion batteries (NIBs) have attracted more and more attention.

[0003] Currently, some new anode materials with potential application prospects have been studied and explored, such as hard carbon, metal alloys, oxides, and sulfides. Among them, metal sulfides stand out due to their unique and controllable morphology and high theoretical capacity. As one of the metal sulfides, nickel sulfide has attracted people's attention due to its relatively high theoretical capacity. Similar to traditional sulfides, the conductivity and ion diffusion coefficient of nickel sulfide metal sulfide materials are usually low, and the material structure may break during lithium / sodium ion insertion / extraction, resulting in a decline in the cycle stability of the material. Therefore, how to improve the electrode conductivity and reduce the volume change caused by the aggregation of nickel sulfide during charge and discharge, and avoid the phenomenon of unstable performance and structure is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] To solve the above technical problems, the present invention proposes an in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material and its preparation method and application.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material preparation method, comprising the following steps:

[0007] Mix a nickel compound with an aqueous solution of few-layer MXene and react under ultrasonic conditions using electrostatic adsorption to obtain an intermediate product; disperse the intermediate product and a sulfurizing agent in an organic solvent for in-situ sulfidation, and after the reaction, wash and anneal the obtained product to obtain the Ni 9 S 8 nanorod / MXene composite anode material.

[0008] Advantages: Two-dimensional (2D) materials exhibit excellent electrochemical properties due to their special structural morphology and surface / interface characteristics, and are widely used in batteries, such as graphene, transition metal disulfides, and so on. In recent years, two-dimensional transition metal carbides or nitrides (abbreviated as MXene) have attracted extensive attention due to their unique structures and electronic characteristics, and have been widely studied in the fields of energy storage, water treatment, biology, and sensors. In this invention, Ni 9 S 8 nanorod / MXene composite anode material is synthesized by in-situ sulfidation through a high-temperature solvent method. By introducing MXene, the unstable electrochemical properties of nickel sulfide are improved through structural design at the nanoscale by combining with Ni 9 S 8 . Through an organic high-temperature in-situ sulfidation method, Ni 9 S 8 nanorods with uniform size are in-situ combined on few-layer MXene with a flat sheet-like structure to obtain a novel two-dimensional composite electrode material with a clear structure. This invention effectively combines the characteristics of high capacity and excellent electrochemical activity of Ni 9 S 8 nanorods with the high conductivity and ion mobility of MXene, forming a faster electron transfer channel, improving the conductivity and ion transport rate of the material; MXene nanosheets as spacers effectively prevent the aggregation and volume expansion of Ni 9 S 8 nanorods during charge and discharge processes. Ni 9 S 8 nanorods as support materials effectively hinder the rearrangement and collapse of MXene nanosheets. Applied to lithium / sodium ion batteries, it has a high energy density, good rate performance, and good cycle stability, and has good reversibility. After 600 cycles, the capacity retention rate is above 99%, and it has extremely broad application prospects.

[0009] Preferably, the nickel compound includes NiCl 2 , NiAc 2 , NiSO 4 , Ni(NO 3 ) 2 and one or any combination of hydrates of the above compounds.

[0010] Preferably, the concentration of the aqueous solution of few-layer MXene is 30-100 mg / mL.

[0011] Preferably, the power of the ultrasonic wave is 10-90%, and the time is 0.5-2 h.

[0012] Preferably, after the reaction using the electrostatic adsorption, freeze-drying treatment is further included;

[0013] The time of the freeze-drying is 12-24 h.

[0014] Beneficial effects: In the present invention, positively charged Ni 2+ is adsorbed onto the surface of negatively charged few-layer MXene under the action of electrostatic adsorption.

[0015] Preferably, the process of dispersing the intermediate product and the sulfurizing agent in an organic solvent specifically includes the following steps:

[0016] Disperse the intermediate product in an organic solvent, heat to remove water and oxygen under a protective atmosphere, and then add the sulfurizing agent and mix evenly.

[0017] Preferably, the organic solvent includes one or any several of oleylamine, stearic acid, and monoglyceryl stearate.

[0018] Preferably, the protective atmosphere includes one of nitrogen, argon, or helium.

[0019] Preferably, the temperature for heating to remove water and oxygen is 100-180 °C, and the time is 0.5-2 h.

[0020] Beneficial effects: The organic solvent in the present invention can passivate the surface of Ni 9 S 8 / MXene to prevent it from being oxidized during the heating process.

[0021] Preferably, the sulfurizing agent includes C 4 H 10 S, C 4 H 10 O 2 S 2 、C 12 H 26 S、CH 3 SH、C 3 H 8 S and C 2 H 6 OS, or one or any several of them.

[0022] Beneficial effects: The above sulfurizing agent is easy to obtain and easy to remove in the subsequent reaction process.

[0023] Preferably, the temperature for in-situ vulcanization is 220~300 °C, and the time is 0.5~2 hours.

[0024] Preferably, the temperature for annealing is 350~550 °C, and the time is 0.5~4 hours.

[0025] Preferably, the washing is carried out using an extractant;

[0026] The extractant is one or any combination of ethanol, methanol, ether, cyclohexane, vegetable oil, and chloroform;

[0027] The number of washing times is 1 - 10 times.

[0028] Beneficial effects: Since the solid product formed after the reaction is difficult to recover, it can be dispersed in a non-polar solvent. After the sample is dispersed in cyclohexane, when a polar solvent is added, the stability of the dispersion is destroyed, forming Ni 9 S 8 / MXene precipitate. In order to avoid the precipitated powder still carrying oleylamine, the heat treatment of the material in the present invention can completely remove the oleylamine residue.

[0029] A preparation method of an in-situ vulcanized Ni 9 S 8 nanorod / MXene composite anode material to obtain an in-situ vulcanized Ni 9 S 8 nanorod / MXene composite anode material, the Ni 9 S 8 nanorod / MXene composite anode material exhibits the morphology of Ni 9 S 8 nanorods and MXene nanosheets, improving the electrochemical activity of the material.

[0030] Beneficial effects: The Ni 9 S 8 nanorod / MXene composite anode material obtained in the present invention has a graphene-like clear nanolayered structure, which can improve the electronic conductivity and transport rate of lithium ions, increase the specific surface area of the electrode material, increase the active sites for the reaction, and utilize MXene and Ni 9 S 8 nanorod composites for structural design at the nanoscale to improve stability, providing stable cycling performance and rate performance.

[0031] An application of an in-situ vulcanized Ni 9 S 8 nanorod / MXene composite anode material in electrode materials.

[0032] Preferably, the electrode material is a negative electrode material for a lithium-ion battery or a negative electrode material for a sodium-ion battery.

[0033] A method for preparing a battery electrode includes the following steps:

[0034] (1) Mix and stir polyvinylidene fluoride powder and N-methylpyrrolidone for 2 h to obtain a mixed solution;

[0035] (2) Grind the above Ni 9 S 8 nanorod / MXene composite negative electrode material powder and SP powder (conductive carbon black), add them to the mixed solution obtained in step (1), continue to stir for 2 h, then evenly coat them on a copper foil, place them in a vacuum oven for drying and cutting to obtain a battery electrode sheet.

[0036] Compared with the prior art, the present invention has the following advantages and technical effects:

[0037] In the Ni 9 S 8 nanorod / MXene composite negative electrode material provided by the present invention, the MXene nanosheets and Ni 9 S 8 nanorods cooperate with each other. Its porous channel structure increases more active sites, which is beneficial to the movement and storage of lithium / sodium ions in the electrode material, promotes better contact between the active substance and the electrolyte, and is beneficial to the Ni 9 S 8 nanorod / MXene composite negative electrode material to exhibit excellent electrochemical performance as an active substance during charge and discharge, showing good reversibility and cycle stability. Moreover, the preparation method provided by the present invention is simple and environmentally friendly, and the obtained electrode material has excellent electrochemical performance, which is conducive to popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0039] Figure 1 is a sample scanning diagram of the Ni 9 S 8 nanorod / MXene composite negative electrode material prepared in Example 1 of the present invention;

[0040] Figure 2 is an XRD pattern of the Ni 9 S 8 nanorod / MXene composite negative electrode material prepared in Example 1 of the present invention;

[0041] Figure 3The capacity of the lithium battery obtained in Example 3 of the present invention after 600 cycles at a current density of 0.5 A / g;

[0042] Figure 4 The capacity of the sodium-ion battery obtained in Example 4 of the present invention after 800 cycles at a current density of 0.5 A / g;

[0043] Figure 5 The capacity of the lithium-ion battery obtained in Example 3 of the present invention at different rates;

[0044] Figure 6 The capacity of the sodium-ion battery obtained in Example 4 of the present invention at different rates. Detailed implementation manners

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0046] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0047] The embodiment of the present invention provides a preparation method of an in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material, including the following steps:

[0048] Mix a nickel compound with a few-layer MXene aqueous solution, and react under ultrasonic conditions using electrostatic adsorption to obtain an intermediate product; disperse the intermediate product and a sulfurizing agent in an organic solvent for in-situ sulfurization, and after the reaction is completed, wash and anneal the obtained product to obtain the Ni 9 S 8 nanorod / MXene composite anode material.

[0049] The present invention effectively combines the characteristics of high capacity and excellent electrochemical activity of Ni 9 S 8 nanorods with the high conductivity and ion migration of MXene, enhances the specific surface area of the composite material, improves the conductivity, and provides a fast channel for the transfer of electrons / ions, improving the conductivity and ion transport rate of the material; MXene nanosheets act as spacers and buffer layers, effectively preventing the aggregation and volume expansion of Ni 9 S 8 nanorods during the charge and discharge process, Ni 9 S8 As a supporting material, the nanorods effectively hinder the rearrangement and collapse of MXene nanosheets, alleviating the electrochemical and structural instabilities caused by large volume changes. The Ni 9 S 8 When the nanorod / MXene composite anode material is applied to lithium / sodium ion batteries, the lithium / sodium ion batteries can have a high energy density, good rate performance, and good cycle stability, with good reversibility. The capacity retention rate is above 99% after 600 cycles.

[0050] In a preferred embodiment, the nickel-containing compound includes NiCl 2 , NiAc 2 , NiSO 4 , Ni(NO 3 ) 2 and one or any combination of hydrates of the above compounds.

[0051] In a preferred embodiment, the concentration of the aqueous solution of few-layer MXene is 30-100 mg / mL, preferably 50 mg / mL.

[0052] In a preferred embodiment, the power of the ultrasonic wave is 10-90%, preferably 90%, and the time is 0.5-2 h, preferably 0.5 h.

[0053] In a preferred embodiment, after the reaction using electrostatic adsorption, freeze-drying treatment is further included;

[0054] The time of freeze-drying is 12-24 h, preferably 12 h.

[0055] In a preferred embodiment, the process of dispersing the intermediate product and the sulfurizing agent in an organic solvent specifically includes the following steps:

[0056] Disperse the intermediate product in an organic solvent, heat it under a protective atmosphere to remove water and oxygen, and then add the sulfurizing agent and mix evenly.

[0057] In a preferred embodiment, the organic solvent includes one or any combination of oleylamine, stearic acid, and monoglyceride stearate, preferably oleylamine.

[0058] In a preferred embodiment, the protective atmosphere includes one of nitrogen, argon, or helium, preferably argon.

[0059] In a preferred embodiment, the temperature for heating to remove water and oxygen is 100-180 °C, preferably 140 °C, and the time is 0.5-2 h, preferably 0.5 h.

[0060] In a preferred embodiment, the sulfurizing agent includes C4 H 10 S, C 4 H 10 O 2 S 2 , C 12 H 26 S, CH 3 SH, C 3 H 8 S and C 2 H 6 One or any combination of H, S, and C, preferably C 12 H 26 S, C 2 H 6 OS and C 4 H 10 O 2 S 2 One of them.

[0061] In a preferred embodiment, the temperature for in-situ sulfidation is 220 - 300 °C, preferably 250 °C, and the time is 0.5 - 2 h, preferably 0.5 h.

[0062] In a preferred embodiment, the temperature for annealing is 350 - 550 °C, preferably 400 °C, and the time is 0.5 - 4 h, preferably 1 h.

[0063] In a preferred embodiment, the washing is performed using an extractant;

[0064] The extractant is one or any combination of ethanol, methanol, ether, cyclohexane, vegetable oil, and chloroform, preferably a mixed solution obtained by mixing cyclohexane and ethanol in a volume ratio of 1:3;

[0065] The number of washing times is 1 - 10 times, preferably 3 times.

[0066] The embodiment of the present invention also provides an in-situ sulfided Ni 9 S 8 nanorod / MXene composite anode material prepared by the preparation method of the in-situ sulfided Ni 9 S 8 nanorod / MXene composite anode material, and the Ni 9 S 8 nanorod / MXene composite anode material exhibits the morphology of Ni 9 S 8 nanorods and MXene nanosheets, improving the electrochemical activity of the material.

[0067] The MXene with a graphene-like clear nanolayered structure provided by the present invention can improve the electronic conductivity and transport rate of lithium ions, increase the specific surface area of the electrode material, and increase the active sites for the reaction. By using the composite of MXene and Ni 9 S 8 nanorods for structural design at the nanoscale to improve stability and provide stable cycling performance and rate performance.

[0068] An embodiment of the present invention also provides an application of an in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material in an electrode material.

[0069] In a preferred embodiment, the electrode material is a lithium-ion battery anode material or a sodium-ion battery anode material.

[0070] An embodiment of the present invention also provides a preparation method for a battery electrode, including the following steps:

[0071] (1) Mix and stir polyvinylidene fluoride powder with N-methylpyrrolidone for 2 h to obtain a mixed solution;

[0072] (2) Grind the above-mentioned Ni 9 S 8 nanorod / MXene composite anode material powder and SP powder (conductive carbon black), add them to the mixed solution obtained in step (1), continue to stir for 2 h, then evenly coat it on a copper foil, place it in a vacuum oven for drying and cutting to obtain a battery electrode sheet.

[0073] Unless otherwise specified, room temperature in the embodiments of the present invention is calculated as 25 ± 2 °C.

[0074] All raw materials used in the embodiments of the present invention are commercially available;

[0075] The preparation method for the few-layer MXene aqueous solution in the embodiments of the present invention includes the following steps:

[0076] Add 3.2 g of LiF to 40 ml of HCl (9 mol / L) solution, stir in a polytetrafluoroethylene reaction kettle at 40 °C for half an hour to obtain an HCl / LiF solution, then slowly add 2 g of Ti 3 AlC 2 to it, and stir for 48 hours for the reaction. After the reaction is completed, wash the mixed solution with deionized water multiple times until the pH of the supernatant is close to neutral. Subsequently, add 400 ml of deionized water and ultrasonicate for 1 hour to obtain a few-layer MXene aqueous solution.

[0077] Example 1

[0078] An in-situ sulfurized Ni9 S 8 Preparation method of nanorod / MXene composite anode material, comprising the following steps:

[0079] (1) Dissolve 2 mmol of NiCl 2 ·6H 2 O in 25 mL of few-layer MXene aqueous solution (50 mg / mL), ultrasonically vibrate at 90% power for 0.5 h, then filter by suction and freeze-dry for 12 h to obtain intermediate product A;

[0080] (2) Pour the intermediate product A obtained in step (1) and 80 mL of oleylamine into a three-necked flask, stir and heat to 140 °C under an argon atmosphere, keep warm for 0.5 h, then remove water vapor and air and cool to room temperature, and then add 40 mL of C 12 H 26 S, and then continuously react at 250 °C for 0.5 h to obtain intermediate product B;

[0081] (3) Finally, disperse the intermediate product B in a mixed solvent obtained by mixing 100 mL of cyclohexane and ethanol in a volume ratio of 1:3, and perform heat treatment at 400 °C for 1 h under an argon atmosphere to obtain Ni 9 S 8 nanorod / MXene composite anode material.

[0082] Example 2

[0083] A preparation method of a battery electrode, comprising the following steps:

[0084] (1) Take 10 mg of polyvinylidene fluoride (PVDF) powder and pour it into 450 mg of N-methylpyrrolidone (NMP) solution with a concentration of 99.9%, stir for 2 h to obtain a mixed solution;

[0085] (2) Take 75 mg of the Ni 9 S 8 nanorod / MXene composite anode material powder obtained in Example 1 and 15 mg of SP powder (conductive carbon black), grind them in an agate mortar, add them to the mixed solution obtained in step (1), continue to stir for 2 h, and then evenly coat them on a copper foil;

[0086] (3) Place the aluminum foil coated with the active substance obtained in step (2) in a vacuum oven, dry it at 60 °C for 12 h, and cut out an electrode sheet with a diameter of 12 mm.

[0087] Example 3

[0088] A lithium-ion battery, the preparation method of which comprises the following steps:

[0089] Using metallic lithium as the positive electrode and the electrode sheet prepared in Example 2 as the negative electrode, a lithium-ion battery button cell was assembled in a glove box using lithium hexafluorophosphate electrolyte (LB-002) and a Celgard 2500 separator. Among them, 80 μL of electrolyte was added to the lithium-ion battery.

[0090] Example 4

[0091] A sodium-ion battery, the preparation method of which comprises the following steps:

[0092] Using metallic sodium as the positive electrode and the electrode sheet prepared in Example 2 as the negative electrode, a sodium-ion battery button cell was assembled in a glove box using sodium perchlorate electrolyte (NC-019) and a glass fiber separator. Among them, 100 μL of electrolyte was added to the sodium-ion battery.

[0093] Example 5

[0094] A preparation method of an in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material, comprising the following steps:

[0095] (1) Dissolve 2 mmol of NiSO 4 in 25 mL of few-layer MXene aqueous solution (50 mg / mL), ultrasonic vibrate at 90% power for 0.5 h, then filter by suction and freeze-dry for 12 h to obtain intermediate product A;

[0096] (2) Pour the intermediate product A obtained in step (1) and 80 mL of oleylamine into a three-necked flask, stir and heat to 140 °C under an argon atmosphere, keep warm for 0.5 h, then remove water vapor and air, cool to room temperature, and then add 40 mL of C 2 H 6 OS, and then continuously react at 250 °C for 0.5 h to obtain intermediate product B;

[0097] (3) Finally, disperse the intermediate product B obtained in step (2) in a mixed solvent obtained by mixing 100 mL of cyclohexane and ethanol in a volume ratio of 1:3, and heat-treat at 400 °C for 1 h under an argon atmosphere to obtain Ni 9 S 8 nanorod / MXene composite anode material.

[0098] Example 6

[0099] A preparation method of an in-situ sulfurized Ni 9 S 8 nanorod / MXene composite anode material, comprising the following steps:

[0100] (1) Dissolve 2 mmol of NiSO4 Dissolve it in 25 mL of few-layer MXene aqueous solution (50 mg / mL), ultrasonically vibrate at 90% power for 0.5 h, then perform suction filtration and freeze-dry for 12 h to obtain intermediate product A;

[0101] (2) Pour the intermediate product A obtained in step (1) and 80 mL of oleylamine into a three-necked flask. After stirring and heating to 140 °C under an argon atmosphere and keeping warm for 0.5 h, remove water vapor and air, cool to room temperature, and then add 40 mL of C 4 H 10 O 2 S 2 , and then continuously react at 250 °C for 0.5 h to obtain intermediate product B;

[0102] (3) Finally, disperse the intermediate product B obtained in step (2) in a mixed solvent obtained by mixing 100 mL of cyclohexane and ethanol in a volume ratio of 1:3, and perform heat treatment at 400 °C for 1 h under an argon atmosphere to obtain the Ni 9 S 8 nanorod / MXene composite anode material.

[0103] Figure 1 This is the sample scanning diagram of the Ni 9 S 8 nanorod / MXene composite anode material obtained in Example 1 of the present invention; it can be observed from the figure that the Ni 9 S 8 nanorods are successfully synthesized and effectively combined with few-layer MXene with a clear plate-like structure. The combination of different structures leads to an increase in the specific surface area.

[0104] Figure 2 This is the XRD pattern of the Ni 9 S 8 / MXene composite material and few-layer MXene obtained in Example 1. It can be seen from the figure that MXene has a (002) characteristic peak at 7.9°. The (002) characteristic peak of MXene is also observed in the Ni 9 S 8 / MXene composite material, but this characteristic peak is broadened, indicating that the grain size of the MXene crystal will be reduced during the synthesis of Ni 9 S 8 nanorods.

[0105] Figure 3 This is for Example 3 of the present invention with Ni 9 S 8The capacity of the lithium battery prepared with the nanorod / MXene composite anode material as the anode material after cycling at a current density of 0.5 A / g; as can be seen from the figure, after cycling 600 times at a current density of 0.5 A / g, the capacity of the lithium-ion battery can reach 451.7 mAh / g, and the Coulomb efficiency remains above 98.6%. The capacity increases during the cycling process and stabilizes after 170 cycles, which is due to the strong synergistic effect between MXene and Ni 9 S 8 nanorods.

[0106] Figure 4 In Example 4 of the present invention, the capacity of the sodium-ion battery prepared with the Ni 9 S 8 nanorod / MXene composite anode material as the anode material after cycling at a current density of 0.5 A / g; as can be seen from the figure, after cycling 800 times at a current density of 0.5 A / g, the capacity of the sodium-ion battery with the MXene material can reach 275 mAh / g, and the Coulomb efficiency remains above 98.5%. The sodium-ion battery has stable cycling performance and no obvious capacity reduction problem during the whole cycling process.

[0107] Figure 5 In Example 3 of the present invention, the capacity of the lithium-ion battery prepared with the Ni 9 S 8 nanorod / MXene composite anode material as the anode material at different rates. As can be seen from the figure, the reversible discharge capacities of the Ni 9 S 8 nanorod / MXene composite material electrode are 810.2 mAh / g, 456.2 mAh / g, 383.1 mAh / g, 348.6 mAh / g, 314.9 mAh / g, and 283.3 mAh / g at 0.1 - 4 A / g respectively. When the current density returns to 0.5 A / g, the reversible charge-discharge capacity recovers to ~409.3 mAh / g, even exceeding the initial capacity, which further indicates that the Ni 9 S 8 nanorod / MXene composite material can maintain a relatively high capacity while having excellent stability, good reversibility, and post-activation characteristics.

[0108] Figure 6 In Example 4 of the present invention, the capacity of the sodium-ion battery prepared with the Ni 9 S 8 nanorod / MXene composite anode material as the anode material at different rates. Ni 9 S 8The reversible discharge capacities of the nanorod / MXene composite electrode material at 0.1 - 4 A / g are 570 mAh / g, 258.88 mAh / g, 225.55 mAh / g, 190.6 mAh / g, 168.2 mAh / g, and 150.9 mAh / g respectively. When the current density is restored to 0.5 A / g, the reversible charge-discharge capacity is restored to ~230.3 mAh / g. After high-rate charge and discharge, the electrode material is activated, the specific capacity is increased, enabling the battery to have good stability and excellent rate performance.

[0109] Comparative Example 1

[0110] A preparation method of an MXene negative electrode material, which is different from that of Example 1 in that nickel chloride hexahydrate (NiCl 2 ·6H 2 O) is not added in step (1), and specifically includes the following steps:

[0111] The few-layer MXene aqueous solution (50 mg / mL) is ultrasonically vibrated for 0.5 hours, then filtered by suction and freeze-dried for 12 hours to obtain the MXene negative electrode material, which is directly used for the preparation of lithium / sodium ion batteries.

[0112] The preparation method of the electrode is the same as that of Example 2.

[0113] The preparation method of the lithium / sodium ion battery is the same as that of Examples 3 and 4.

[0114] It is found that when the few-layer MXene material obtained from Comparative Example 1 is used as the negative electrode material, the capacity of the few-layer MXene is relatively low, but its stability is good during the cycling process and the capacity increases. The capacity of the lithium ion battery can reach 39.87 mAh / g after cycling 600 times at a current density of 0.5 A / g, and the capacity of the sodium ion battery can reach 105.39 mAh / g after cycling 800 times at a current density of 0.5 A / g.

[0115] Comparative Example 2

[0116] A preparation method of a negative electrode material, which is different from that of Example 1 only in that the MXene aqueous solution is not added in step (1), and specifically includes the following steps:

[0117] (1) Pour 2 mmol of NiCl 2 ·6H 2 O and 80 mL of oleylamine into a three-necked flask, stir and heat to 140 °C under an argon atmosphere, keep warm for 0.5 h, then remove water vapor and air and cool to room temperature, and then add 40 mL of C 12 H 26 S, and then continuously react at 250 °C for 0.5 h to obtain the intermediate product B;

[0118] (2) Finally, disperse the intermediate product B in a mixed solvent obtained by mixing 100 mL of cyclohexane and ethanol in a volume ratio of 1:3, and heat-treat it at 400 °C for 1 h under an argon atmosphere to obtain Ni 9 S 8 nanorod anode material.

[0119] The preparation method of the electrode is the same as that in Example 2.

[0120] The preparation method of the lithium / sodium ion battery is the same as that in Example 3.

[0121] It was found that when the Ni 9 S 8 nanorod material is used as the anode material, the cycling stability of the Ni 9 S 8 nanorod anode material is extremely poor, and the capacity loss is more than 90% after only 50 cycles. The specific capacity of the lithium-ion battery can reach 30.59 mAh / g after cycling at a current density of 0.5 A / g, and the specific capacity of the sodium-ion battery can reach 12.4 mAh / g after cycling at a current density of 0.5 A / g.

[0122] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing an in-situ sulfurized Ni9S8 nanorod / MXene composite negative electrode material, characterized in that: The following steps are involved: The nickel-containing compound is mixed with a few-layer MXene aqueous solution, and reacted by electrostatic adsorption under ultrasonic conditions to obtain an intermediate product; the intermediate product and a vulcanizing agent are dispersed in an organic solvent for in-situ vulcanization, and after the reaction is completed, the obtained product is washed and annealed to obtain the Ni9S8 nanorod / MXene composite negative electrode material; The in-situ vulcanization temperature is 250°C and the time is 0.5 hours; The annealing temperature is 400° C. and the annealing time is 1 hour.

2. The method for preparing an in-situ sulfurized Ni9S8 nanorod / MXene composite negative electrode material according to claim 1, characterized in that: The nickel-containing compound includes one or any several of NiCl2, NiAc2, NiSO4, Ni(NO3)2 and hydrates of the above compounds.

3. The method for preparing an in-situ sulfurized Ni9S8 nanorod / MXene composite negative electrode material according to claim 1, characterized in that: The concentration of the aqueous solution of the few-layer MXene is 30 to 100 mg / mL.

4. The method for preparing an in-situ sulfurized Ni9S8 nanorod / MXene composite negative electrode material according to claim 1, characterized in that: The power of the ultrasound is 10-90%, and the time is 0.5-2h.

5. The method for preparing an in-situ sulfurized Ni9S8 nanorod / MXene composite negative electrode material according to claim 1, characterized in that: The process of dispersing the intermediate product and the vulcanizing agent in an organic solvent specifically comprises the following steps: dispersing the intermediate product in an organic solvent, heating under a protective atmosphere to expel water and oxygen, and then adding the vulcanizing agent and mixing evenly.

6. The method for preparing an in-situ sulfurized Ni9S8 nanorod / MXene composite negative electrode material according to claim 5, characterized in that: The vulcanizing agent includes C4H 10 S, C4H 10 O2S2、C 12 H 26 One or any combination of S, CH3SH, C3H8S and C2H6OS.

7. An in-situ sulfided Ni9S8 nanorod / MXene composite negative electrode material prepared by the method for preparing an in-situ sulfided Ni9S8 nanorod / MXene composite negative electrode material as described in any one of claims 1 to 6.

8. Use of an in-situ sulfided Ni9S8 nanorod / MXene composite negative electrode material as described in claim 7 in electrode materials.

Images