阅读说明：本技术 中空介孔碳球负载氢氧化镍/硫复合材料的制备方法 (Preparation method of hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material ) 是由 袁磊 韩秋瑞 兰颖洁 付永胜 汪信 吴震 周焱 陈鹏 于 2019-09-05 设计创作，主要内容包括：本发明公开了一种中空介孔碳球负载氢氧化镍/硫复合材料的制备方法。所述方法先将中空介孔碳球充分分散于水中,再依次加入硫酸镍和过硫酸钾水溶液,并缓慢加入氨水,得到中空介孔碳球负载氢氧化镍复合材料,然后将中空介孔碳球负载氢氧化镍复合材料和硫混合,在150～155℃下进行热熔融挥硫反应,得到中空介孔碳球负载氢氧化镍/硫复合材料。本发明采用的中空介孔碳球具有较大的比表面,可以防止体积膨胀效应和提高活性物质载量,抑制多硫化物的溶解,另一方面,中空介孔碳球负载的片层氢氧化镍具有超薄的结构,可以提供更多的活性位点和强有力的化学吸附多硫化物,从而达到抑制穿梭效应,制备的电池具有高容量、倍率性好且循环寿命长的优点。(The invention discloses a preparation method of a hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material. The method comprises the steps of fully dispersing hollow mesoporous carbon spheres in water, sequentially adding aqueous solution of nickel sulfate and potassium persulfate, slowly adding ammonia water to obtain a hollow mesoporous carbon sphere-loaded nickel hydroxide composite material, mixing the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material with sulfur, and carrying out hot melting sulfur volatilization reaction at 150-155 ℃ to obtain the hollow mesoporous carbon sphere-loaded nickel hydroxide/sulfur composite material. The hollow mesoporous carbon spheres adopted by the invention have larger specific surface, can prevent volume expansion effect, improve the loading capacity of active substances and inhibit the dissolution of polysulfide, and on the other hand, the lamellar nickel hydroxide loaded on the hollow mesoporous carbon spheres has an ultrathin structure and can provide more active sites and strong chemical adsorption polysulfide so as to achieve the effect of inhibiting shuttle effect, and the prepared battery has the advantages of high capacity, good multiplying power and long cycle life.)

1. The preparation method of the hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material is characterized by comprising the following specific steps of:

step 1, loading a nickel hydroxide composite material on a hollow mesoporous carbon sphere:

fully dispersing hollow mesoporous carbon spheres in water under an ultrasonic condition, sequentially adding a nickel sulfate aqueous solution and a potassium persulfate aqueous solution, slowly adding ammonia water, reacting under a stirring condition, centrifuging after the reaction is finished, washing a solid phase, and drying to obtain the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material;

step 2, preparing the hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material:

and mixing the hollow mesoporous carbon sphere loaded nickel hydroxide composite material with sulfur, and carrying out hot melting and sulfur volatilization reaction at 150-155 ℃ to obtain the hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material.

2. The preparation method according to claim 1, wherein in the step 2, the mass ratio of the hollow mesoporous carbon spheres to the nickel sulfate to the potassium persulfate is 1: 50: 2-1: 80: 2.

3. the preparation method according to claim 1, wherein in the step 2, the reaction time is 10-12 h.

4. The preparation method according to claim 1, wherein in the step 2, the mass ratio of the nickel hydroxide composite material loaded on the hollow mesoporous carbon spheres to the sulfur is 1: 3-1: 4.

Technical Field

The invention belongs to the technical field of positive electrode materials of lithium-sulfur batteries, and relates to a preparation method of a hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material.

Background

The lithium-sulfur battery has very high theoretical specific capacity (1675mAh g)^-1) And energy density (2600Wh kg)^-1) And elemental sulfur is cheap and readily available, making it one of the attractive next-generation low-cost energy storage technologies. However, the lithium sulfur battery has many problems, such as fast self-capacity fading, low sulfur positive electrode conductivity, polysulfide "shuttle effect", lithium ion deposition, and structural change due to volume change during charge and discharge. Among the above problems, the shuttle effect has the greatest influence on the performance of the lithium sulfur battery and is the most difficult problem to solve. Therefore, the search and development of new positive electrode materials for lithium-sulfur batteries has been a problem that needs to be solved.

In the aspect of improving the positive electrode material of the lithium-sulfur battery, the hollow carbon sphere/sulfur composite material becomes a research hotspot. The hollow carbon spheres have good conductivity, and also have the advantages of high porosity, strong adsorption capacity, low cost and the like. However, since the chemical interaction between nonpolar carbon and polar polysulfides is weak, it is difficult to completely suppress the diffusion of polysulfides by simple physical adsorption, resulting in a drastic deterioration of performance during subsequent cycles.

Aiming at the problem of capacity attenuation of the hollow carbon sphere/sulfur composite material, Wu et al adopt a flexible layer-by-layer self-assembly strategy to coat polyelectrolyte multilayer (PEMs) and graphene sheets on the surface of the hollow carbon sphere/sulfur composite material,composite electrodes were prepared at 1A g^-1Has very stable stability for 200 cycles at current density, and the average coulomb efficiency is as high as 99% (Nano letters,2016,16(9): 5488-. However, the rate capability and cycle life of the electrode material are difficult to meet the requirements of current applications. Ni and the like react the hollow carbon sphere/sulfur composite material with potassium permanganate to generate a layer of polar manganese dioxide as a protective layer, and polysulfide dissolution (ACS applied materials) can be effectively inhibited through physical and chemical adsorption at the same time&interfaces,2017,9(40): 34793-. However, the resulting manganese dioxide has a thick shell layer, so that the sulfur content can only reach 60%, and the low energy density makes it difficult to apply the manganese dioxide.

Disclosure of Invention

In order to effectively inhibit the shuttle effect of polysulfide in the charge-discharge process and improve the utilization rate of active substance sulfur and the cycle performance of a battery, the invention provides a preparation method of a hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material which can be used as a lithium-sulfur battery cathode material.

The technical scheme of the invention is as follows:

the preparation method of the hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material comprises the following specific steps:

step 1, loading a nickel hydroxide composite material on a hollow mesoporous carbon sphere:

fully dispersing hollow mesoporous carbon spheres in water under an ultrasonic condition, sequentially adding a nickel sulfate aqueous solution and a potassium persulfate aqueous solution, slowly adding ammonia water, reacting under a stirring condition, centrifuging after the reaction is finished, washing a solid phase, and drying to obtain the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material;

step 2, preparing the hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material:

and mixing the hollow mesoporous carbon sphere loaded nickel hydroxide composite material with sulfur, and carrying out hot melting and sulfur volatilization reaction at 150-155 ℃ to obtain the hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material.

In the step 2, the mass ratio of the hollow mesoporous carbon spheres to the nickel sulfate to the potassium persulfate is 1: 50: 2-1: 80: 2, the nickel hydroxide obtained under the condition can just wrap the hollow mesoporous carbon spheres, and the obtained composite material has uniform appearance.

In the step 2, the reaction time is 10-12 h, when the temperature reaches 150-155 ℃, sulfur has strong fluidity and enters the hollow mesoporous carbon spheres under the capillary action, and the sulfur volatilization loss is small at the temperature.

In the step 2, the mass ratio of the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material to sulfur is 1: 3-1: 4.

Compared with the prior art, the invention has the following advantages:

the method is simple and convenient to operate and low in production cost. Compared with the common carbon/sulfur composite material, the three-dimensional hollow mesoporous carbon spheres have larger specific surface, can prevent volume expansion effect and improve the loading capacity of active substances, and also can well inhibit the dissolution of polysulfide on the aspect of physical constraint. On the other hand, the hollow mesoporous carbon sphere-loaded lamellar nickel hydroxide has an ultrathin structure and can provide more active sites and powerful chemical adsorption polysulfide, so that the shuttle effect is inhibited, the electrochemical performance of the battery is stabilized, meanwhile, the sulfur content in the composite material is up to 80%, and the prepared battery has the advantages of high capacity, good rate capability and long cycle life.

Drawings

Fig. 1 is a scanning electron microscope image of the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material prepared by the invention.

FIG. 2 is a transmission electron microscope image of the hollow mesoporous carbon sphere loaded nickel hydroxide composite material prepared by the present invention.

FIG. 3 is a performance diagram of the hollow mesoporous carbon sphere loaded nickel hydroxide composite material prepared by the invention and sulfur in a mass ratio of 1:4 circulating for 800 cycles at 1C.

FIG. 4 is a performance diagram of the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material of comparative example 1 and sulfur in a mass ratio of 1:5, cycled at 1C for 800 cycles.

Detailed Description

The present invention will be described in more detail with reference to the following examples and the accompanying drawings.

In the following examples, the hollow mesoporous carbon spheres were prepared according to the reference (ACS nano,2016,10(4): 4579-4586).

Example 1

(1) Preparing a hollow mesoporous carbon sphere loaded nickel hydroxide composite material:

under the ultrasonic condition, 30mg of hollow mesoporous carbon spheres are fully dispersed in 8ml of water and subjected to ultrasonic treatment for 1 hour. 1.50g of nickel sulfate was dissolved in 3.2ml of water to prepare solution A, and 60mg of potassium persulfate was dissolved in 4.8m of water to prepare solution B. Slowly dripping the solution A into the hollow mesoporous carbon sphere dispersion liquid, stirring for 0.5h, then slowly dripping the solution B and 0.8ml of ammonia water in sequence, stirring for 1h, and after the reaction is finished, centrifuging, washing for 2 times by deionized water, and drying to obtain the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material.

(2) Preparing a hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material:

loading a nickel hydroxide composite material on a hollow mesoporous carbon sphere and sulfur according to a mass ratio of 1:3, wrapping the mixture with aluminum foil, then placing the wrapped mixture into a reaction kettle, carrying out hot melting sulfur volatilization reaction for 12 hours at the ambient temperature of 155 ℃, and obtaining the hollow mesoporous carbon sphere-loaded nickel hydroxide/sulfur composite material after the reaction is finished.

Example 2

(1) Preparing a hollow mesoporous carbon sphere loaded nickel hydroxide composite material:

fully dispersing 30mg of hollow mesoporous carbon spheres in 8ml of water under the ultrasonic condition, and carrying out ultrasonic treatment for 1 h. 2.40g of nickel sulfate was dissolved in 3.2ml of water to prepare solution A, and 60mg of potassium persulfate was dissolved in 4.8m of water to prepare solution B. Slowly dripping the solution A into the hollow mesoporous carbon sphere dispersion liquid, stirring for 0.5h, then slowly dripping the solution B and 0.8ml of ammonia water in sequence, stirring for 1h, and after the reaction is finished, centrifuging, washing for 2 times by deionized water, and drying to obtain the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material.

(2) Preparing a hollow mesoporous carbon sphere loaded nickel hydroxide/sulfur composite material:

loading a nickel hydroxide composite material on a hollow mesoporous carbon sphere and sulfur according to a mass ratio of 1:4, wrapping the mixture with aluminum foil, then placing the wrapped mixture into a reaction kettle, carrying out hot melting sulfur volatilization reaction for 12 hours at the ambient temperature of 155 ℃, and obtaining the hollow mesoporous carbon sphere-loaded nickel hydroxide/sulfur composite material after the reaction is finished.

Comparative example 1

The comparative example is basically the same as the example 1, except that the mass ratio of the hollow mesoporous carbon sphere-supported nickel hydroxide composite material to sulfur is 1: 5.

The morphology and the performance of the composite materials prepared in the embodiment 1 and the embodiment 2 are similar, and the embodiment 1 is taken as an example. As shown in fig. 1, it is a scanning electron microscope image of the hollow mesoporous carbon sphere loaded with nickel hydroxide prepared in example 1. Therefore, the prepared hollow mesoporous carbon sphere loaded nickel hydroxide has uniform appearance and the diameter of about 280 nm.

As shown in fig. 2, it is a transmission electron micrograph of the hollow mesoporous carbon sphere prepared in example 1 loaded with nickel hydroxide. As can be seen from the figure, the nickel hydroxide nanosheet loaded on the hollow mesoporous carbon sphere is thinner, more active site chemical adsorption polysulfides can be provided, the hollow structure can also improve the sulfur content, and the problem of volume expansion in the discharging process is solved.

Fig. 3 is a performance diagram of the hollow mesoporous carbon sphere-supported nickel hydroxide/sulfur composite cathode material prepared in example 1 cycled at 1C for 800 cycles. As can be seen from the figure, the first discharge specific capacity is 850mAh/g, after 800 cycles, the specific capacity is still 584mAh/g, and the average attenuation of each cycle is 0.33%.

FIG. 4 is a performance diagram of the hollow mesoporous carbon sphere-loaded nickel hydroxide composite material of comparative example 1 and sulfur in a mass ratio of 1:5, cycled at 1C for 800 cycles. The specific discharge capacity of the electrode material prepared according to the proportion is 766mAh/g, after 800 cycles, the specific discharge capacity is reduced to 370mAh/g, and the average attenuation of each cycle is 0.50%. Compared with the embodiment 1, the battery has obviously poorer cycle stability and discharge specific capacity and short cycle life.