阅读说明：本技术 Si-TiO2-C复合纳米线的制备方法及其制品、应用 (Si-TiO2Preparation method of-C composite nanowire, product and application thereof ) 是由 韩美胜 于杰 李佳洋 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种Si-TiO<Sub>2</Sub>-C复合纳米线的制备方法及其制品、应用,本发明制备方法将钛酸四丁酯聚合物和四氯化硅的混合溶液作为前驱体密封于高压反应装置并在氩气保护下加热到合适温度使其分解产生气相高压,在气相高压的作用下制备了Si-TiO<Sub>2</Sub>-C复合纳米线,整体制备工艺简单环保、原料丰富易得、制备成本低廉,所制得Si-TiO<Sub>2</Sub>-C复合纳米线具有纳米级均匀分布的Si、TiO<Sub>2</Sub>和C的特殊结构,有利于缓解Si在储锂过程中的体积膨胀并提高其电导率,使其可作为优质负极材料应用于锂离子电池中,有效提高电池的容量、循环性能和倍率性能,拥有极大的应用价值,利于广泛推广应用。(The inventionDiscloses a Si-TiO compound 2 The preparation method of the-C composite nanowire comprises the steps of taking a mixed solution of tetrabutyl titanate polymer and silicon tetrachloride as a precursor, sealing the precursor in a high-pressure reaction device, heating the precursor to a proper temperature under the protection of argon gas to decompose the precursor to generate gas-phase high pressure, and preparing Si-TiO under the action of the gas-phase high pressure 2 The integral preparation process of the-C composite nanowire is simple and environment-friendly, the raw materials are rich and easy to obtain, the preparation cost is low, and the prepared Si-TiO is 2 the-C composite nanowire has Si and TiO uniformly distributed in nano level 2 And the special structure of C is beneficial to relieving the volume expansion of Si in the lithium storage process and improving the conductivity of Si, so that Si can be used as a high-quality cathode material to be applied to a lithium ion battery, the capacity, the cycle performance and the rate performance of the battery are effectively improved, the C has great application value, and the C is beneficial to wide popularization and application.)

1. Si-TiO₂-a method for preparing a composite nanowire, characterized in that: which comprises the following steps:

(1) taking mixed solution of tetrabutyl titanate polymer and silicon tetrachloride solution as a precursor;

(2) sealing: sealing the precursor in a high-pressure reaction device;

(3) gas-phase reaction: the high-pressure reaction device is moved into a heating furnace with inert gas protection for heating so as to decompose the precursor to generate gas-phase high pressure, and Si-TiO with a special structure is synthesized under the action of the gas-phase high pressure₂-C composite nanowires.

2. Si-TiO according to claim 1₂-a method for preparing a composite nanowire, characterized in that: the mass ratio of the tetrabutyl titanate polymer to the silicon tetrachloride solution in the mixed solution is 0.5-5: 1.

3. Si-TiO according to claim 1₂-a method for preparing a composite nanowire, characterized in that: the step (2) specifically comprises the following steps:

(2.1) weighing a proper amount of the mixed solution as a precursor and adding the precursor into a high-pressure reaction device;

(2.2) sealing the high-pressure reaction device in a glove box filled with inert gas.

4. Si-TiO according to claim 1₂-a method for preparing a composite nanowire, characterized in that: the step (3) specifically comprises the following steps:

(3.1) moving the high-pressure reaction device to a heating furnace, introducing inert gas, and heating to 600-900 ℃ at a heating rate of 5-20 ℃/min;

(3.2) after heat preservation is carried out for 0.2-1 h, cooling to room temperature, and taking out the high-pressure reaction device;

(3.3) moving the high-pressure reaction device to a fume hood to open, and obtaining Si-TiO with a special structure₂-C composite nanowires.

5. Si-TiO according to claim 3 or 4₂-a method for preparing a composite nanowire, characterized in that: the inert gas is argon.

6. Si-TiO according to claim 3 or 4₂-a method for preparing a composite nanowire, characterized in that: what is needed isThe Si-TiO₂The diameter of the-C composite nanowire is 100-1000nm, and the length of the-C composite nanowire is 5-20 mu m.

7. Si-TiO according to claim 1₂-a method for preparing a composite nanowire, characterized in that: the Si-TiO compound₂the-C composite nanowire has a micropore structure.

8. Si-TiO2-C composite nanowire prepared by the method of preparing the same according to any one of claims 1 to 7₂-C composite nanowire, characterized in that it is composed of Si and TiO in nanoscale dimensions₂Are uniformly dispersed in C, and Ti-O-C and Si-O-C bonds are formed at the interface.

9. Si-TiO according to claim 8₂-C composite nanowires, characterized in that: the diameter of the material is 100-1000nm, and the length of the material can be controlled within 5-20 μm.

10. An Si-TiO compound for use in the production of the compound according to any one of claims 1 to 7₂Si-TiO prepared by preparation method of-C composite nanowire₂the-C composite nanowire product is applied to a negative electrode material of a lithium ion battery.

Technical Field

The invention relates to the technical field of new materials with an energy storage function, in particular to Si-TiO₂A preparation method of the-C composite nanowire, a product and application thereof.

Background

Under the background that the natural environment deteriorates, the global warming is gradually increased, the whole energy demand is continuously increased, and the storage of the traditional disposable fossil energy tends to be exhausted, the green renewable energy (solar energy, wind energy, tidal energy, geothermal energy and the like) continuously attracts attention in the past decades. However, due to the characteristics of small energy distribution density, difficult storage, intermittence and the like, further research and development of efficient and stable energy storage devices become very important.

Rechargeable batteries are one of the most efficient energy storage devices at present. Lithium ion batteries stand out among various rechargeable batteries because of their wide lithium source, low cost, and excellent performance. Since the introduction of the first commercial lithium ion battery product from sony corporation in 1991, its research has been greatly developed and widely applied to the fields of mobile electronic products, electric vehicles, sustainable energy systems, and the like. The commercially abundant graphite occupies the major lithium ion battery negative electrode material market, but its relatively low theoretical capacity (372mAh g)^-1) And poor rate capability cannot meet the increasing user demands of high energy density and high functional density. Thus, in order to meet the requirements of devices with higher energy density, higher functional density and longer service life, research on the use of replaceable graphite as a negative electrode material has been continuously and highly focused.

The next generation of possible negative electrode materials such as Si, Ge, alloy materials, transition metal oxides andsulfides and the like, in which Si has an ultra-high theoretical specific capacity (4200mAh g)^-1) Are considered to be the most potential alternative materials. But the lithium ion battery has the defects of ultrahigh volume change rate (about 300 percent), low conductivity and the like in the lithium removal/lithium insertion process, so that the lithium ion battery cannot be directly applied to the lithium ion battery at present. Publication No. "CN 104835949B", name "Si-TiO₂The invention patent of-C nano fiber composite film and preparation method and application thereof discloses Si-TiO₂-C nanofiber composite film and preparation method and application thereof, wherein the preparation method comprises the following steps: (1) providing a spinning solution, wherein the spinning solution contains nano silicon powder, a titanium precursor and a carbon precursor; (2) carrying out electrostatic spinning on the spinning solution so as to obtain a nanofiber membrane; (3) pre-oxidizing the nanofiber membrane at 100-300 ℃ in an oxygen-containing atmosphere to obtain a stabilized nanofiber membrane; (4) carbonizing the stabilized nanofiber membrane at 500-1000 ℃ in a non-oxidizing atmosphere to obtain Si-TiO₂A preparation method of the-C composite nanowire. It can relieve the volume change of Si and C during lithium desorption and improve TiO₂The electrochemical activity of the electrolyte effectively improves the specific capacity, rate capability and cycle performance of the battery. But the manufacturing process steps are relatively numerous, spinning, oxidation, carbonization for film forming and cutting are needed, the operation is troublesome, the period is long, the production efficiency is low, and the capacity, the rate capability and the cycle performance of the battery are still further improved.

Disclosure of Invention

Aiming at the defects, the invention aims to provide Si-TiO with simple and environment-friendly process and easy realization₂A preparation method of the-C composite nanowire, a product and application thereof.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

Si-TiO₂-a method for preparing a C composite nanowire comprising the steps of:

(1) taking mixed solution of tetrabutyl titanate polymer and silicon tetrachloride solution as a precursor;

(2) sealing: sealing the precursor in a high-pressure reaction device;

(3) gas-phase reaction: the high-pressure reaction device is moved into a heating furnace with inert gas protection for heating so as to decompose the precursor to generate gas-phase high pressure, and Si-TiO with a special structure is synthesized under the action of the gas-phase high pressure₂-C composite nanowires.

According to a preferable scheme of the invention, the mass ratio of the tetrabutyl titanate polymer to the silicon tetrachloride solution in the mixed solution is 0.5-5: 1.

as a preferable embodiment of the present invention, the step (2) specifically includes the following steps:

(2.1) weighing a proper amount of the mixed solution as a precursor and adding the precursor into a high-pressure reaction device;

(2.2) sealing the high pressure reaction apparatus in a glove box filled with an inert gas, preferably argon.

As a preferable embodiment of the present invention, the step (3) specifically includes the following steps:

(3.1) moving the high-pressure reaction device to a heating furnace, wherein the heating furnace is preferably a tubular furnace, introducing inert gas, the inert gas is preferably argon, and heating to 600-900 ℃ at a heating rate of 5-20 ℃/min;

(3.2) after heat preservation is carried out for 0.2-1 h, cooling to room temperature, and taking out the high-pressure reaction device;

(3.3) opening the high-pressure reaction device to obtain Si-TiO with a special structure₂-C composite nanowires. When opening the high-pressure reactor, attention is paid to the evolution of gas, and the operator should wear corresponding protective tools and operate in a fume hood.

Si-TiO2-C composite nanowire prepared by adopting preparation method₂-C composite nanowires made of Si and TiO of nanometric dimensions₂Is uniformly dispersed in C, forms Ti-O-C and Si-O-C bonds at the interface, and has a large specific surface area and a microporous structure. Si-TiO₂The diameter of the-C composite nanowire is 100-1000nm, and the length of the-C composite nanowire is controllable to be 5-20 mu m. The nano-scale size is 5-20 nm.

A kind of entityApplying the above Si-TiO₂Si-TiO prepared by preparation method of-C composite nanowire₂the-C composite nanowire product is applied to a negative electrode material of a lithium ion battery.

The invention has the beneficial effects that: the preparation method is simple and environment-friendly, various reaction conditions in the process are easy to control, the prepared finished product is safe, the cost is low, the preparation time is short, the yield is high, and the method is favorable for large-scale batch production.

Si-TiO prepared by the invention₂the-C composite nanowire has a special nanoscale uniform dispersion structure, so that the volume change of Si is well relieved, and the conductivity of the-C composite nanowire is effectively improved. Meanwhile, the nanoscale uniform dispersion structure can generate a large amount of phase boundaries, so that a large amount of defects exist, and the defects can store lithium ions, so that the lithium storage capacity can be improved, and the volume change of the lithium storage capacity can be relieved; and also has large specific surface area and microporous structure, which is beneficial to the contact of active substances and electrolyte, and shortens Li⁺Diffusion distance of (2) in favor of extra Li⁺Can alleviate the volume change of the active substance in the circulation process, thereby improving the capacity, the circulation life and the rate capability. The presence of Ti-O-C and Si-O-C bonds may increase the structural stability of the active material during cycling, thereby improving its stability. The nanowire structure has strain relaxation properties that allow its diameter and length to continue to increase without breaking, thereby forming a stable solid electrolyte layer at the interface. In addition, the nanowire structure can bear larger strain than the corresponding block, so that the fracture of the electrode is relieved, and the cycling stability of the electrode is improved.

Si-TiO of the invention₂After the-C composite nanowire is applied to a lithium ion battery cathode material, the-C composite nanowire has good cycle performance and rate capability, higher capacity, good cycle performance and rate capability, and after 200 cycles, the Si-TiO is tested by experiments under the current density of 0.1A/g₂The reversible capacity obtained by-C is up to 1049.3mAh/g, and the corresponding capacity retention rate is 95.7%; Si-TiO after 5000 cycles at a current density of 2A/g₂The reversible capacity obtained by the-C is up to 497.2mAh/g, and the corresponding capacity retention rate is 85.3%; at a current density of 10A/g, Si-TiO₂The reversible capacity obtained by-C is up to 105.4 mAh/g.

The invention is further described with reference to the following figures and examples.

Drawings

FIG. 1 is Si-TiO, obtained at 600 ℃ in example 1 of the invention₂SEM photograph of the C composite nanowire.

FIG. 2 is Si-TiO obtained at 800 ℃ in example 2 of the present invention₂SEM photograph of the C composite nanowire.

FIG. 3 shows Si-TiO obtained in example 2 of the present invention₂-XRD pattern of C composite nanowires.

FIG. 4 shows Si-TiO obtained in example 2 of the present invention₂-XPS survey spectrum of C composite nanowires.

FIG. 5 shows Si-TiO obtained in example 2 of the present invention₂XPS spectra of Si 2p of C composite nanowires.

FIG. 6 shows Si-TiO obtained in example 2 of the present invention₂-XPS spectra of Ti 2p of C composite nanowires.

FIG. 7 shows Si-TiO obtained in example 2 of the present invention₂XPS plot of O1s for C composite nanowires.

FIG. 8 shows Si-TiO obtained in example 2 of the present invention₂XPS plot of C1s for C composite nanowires.

FIG. 9 shows Si-TiO obtained in example 2 of the present invention₂Isothermal adsorption and desorption curves of the-C composite nanowires and the corresponding BJH pore size distribution plot.

FIGS. 10 and 11 are Si-TiO compounds obtained in example 2 of the present invention₂TEM image of the C composite nanowires.

FIG. 12 shows Si-TiO obtained in example 2 of the present invention₂And the-C composite nanowire is used as a lithium battery negative electrode material and has a cycling stability curve at a current density of 0.1A/g.

FIG. 13 shows Si-TiO obtained in example 2 of the present invention₂And the-C composite nanowire is used as a lithium battery negative electrode material and has a cycling stability curve at a current density of 2A/g.

FIG. 14 shows Si-TiO obtained in example 2 of the present invention₂the-C composite nanowire is used as a rate performance curve of a lithium battery negative electrode material.

Detailed Description