CN105720249B - A kind of preparation method of Sn Si alloy-type nano composite powders - Google Patents

Abstract

The invention discloses a method for preparing Sn-Si alloy nanocomposite powder, which belongs to the field of new functional materials. First, the high-purity Sn and high-purity Si blocks are mass-proportioned according to a certain stoichiometric ratio, and then the Sn-Si alloy fast body material is obtained by melting in vacuum induction melting, and the obtained block material is processed under an inert gas environment. Arc evaporation was used to prepare Sn-Si alloy-type composite nanopowder. The average particle size of the Sn-Si alloy type composite nanopowder particles obtained by the method of the invention is in the nanometer scale, and the process route of the method is simple and easy, the synthesis period is short, and the technical parameters are highly controllable.

Description

A kind of preparation method of Sn-Si alloy type nanocomposite powder

technical field

The invention relates to a preparation method of Sn-Si alloy nanocomposite powder, which belongs to the technical field of preparation of nanometer materials and new functional materials.

Background technique

Lithium-ion batteries have become a common product in people's daily life due to their high capacity, long cycle life, and environmental friendliness. As the application field of lithium batteries develops from small portable electronic devices to electric vehicles, aerospace, large military equipment and other markets, people have put forward higher requirements for the performance of lithium batteries. Lithium-ion batteries are mainly composed of cathode, anode, electrolyte, separator and so on. As one of the key electrode materials of lithium-ion batteries, the negative electrode material directly affects its performance, and may become a bottleneck restricting its large-scale application. Therefore, the design and development of new lithium-ion battery anode materials with excellent electrochemical performance is the focus of research and development in the battery industry.

In lithium-ion batteries, the negative electrode materials studied mainly include: graphitized carbon materials, silicon-based materials, tin-based materials, nitrides, alloy materials, and nano-oxides (Wu Yuping, Zhang Hanping, etc. Green Power Materials. Beijing Chemical Industrial Press, 2008). Tin and silicon-based materials have become the research hotspots of negative electrode materials due to their high theoretical lithium storage capacity (Li _4.4 Sn, 994mAh/g; Li _4.4 Si, 4200mAh/g). The researchers further found that after the nanoscale of this kind of alloy material, with the increase of the lithium ion migration channel, the lithium storage energy is further enhanced, so the nano-alloy material has great application potential as a high-performance anode material. Nano-Sn anode materials are easy to agglomerate during charge and discharge, which makes active electrode materials invalid (Bin Lou et al, Graphene-Confined Sn Nanosheets with Enhanced LithiumStorage Capability, Adv. Mater. 2012, 24, 3538-3543), affecting lithium-ion batteries cycle performance. And the main failure mechanism of the nano-Si anode material is the pulverization failure of the anode material due to the large volume change during the charging and discharging process. At present, material compounding has become an effective way to improve the electrochemical performance (such as capacity, cycle performance, etc.) of lithium-ion battery anode materials. Therefore, it can be considered to combine nano-Sn and nano-Si, take advantage of the advantages of both, and work together to improve the stability of the negative electrode material in the cycle of lithium-ion batteries. However, the existing methods for the development of nano-Si and Sn particle materials are still unable to achieve low-cost, high-yield, and size-controllable materials, and there is no report of one-step preparation of Sn-Si alloy nanocomposite powder at home and abroad.

Based on the above background, we adopt vacuum suspension melting preparation technology and evaporation condensation preparation technology to prepare Sn-Si alloy nanocomposite powder with good dispersion and particle size distribution in nanometer scale through short process.

Contents of the invention

The object of the present invention is to provide a method for preparing Sn-Si alloy nanocomposite powder. First, the high-purity Sn and high-purity Si blocks are mass-proportioned according to the stoichiometric ratio, and then the Sn-Si alloy block material is obtained by adjusting the input power in the vacuum induction melting, and the obtained block material is used as the base material. Arc evaporation is carried out under an inert gas environment to prepare composite nanopowder. It is characterized in that it comprises the following steps:

(1) First, mix Sn and Si according to the stoichiometric ratio, and in the high-vacuum suspension melting furnace, adjust the power to melt the Sn block (low melting point, high gasification temperature), and then gradually increase the power, after increasing the power The corresponding power range is 6 ~ 11kW to melt the Si block; after the whole is liquefied, it is suspended for 2 minutes and then cooled to obtain a Sn-Si alloy block material;

(2) Using the prepared Sn-Si alloy bulk material as an anode, in an environment where the volume ratio of hydrogen to inert gas argon is 1:1, a high-intensity arc is formed by discharge, and the arc starting current is 100-250A. The arc voltage is 10-30V, and the evaporation time is 40-60 minutes; solid Sn-Si nanoparticles are formed after evaporation and condensation.

The above step (1) is used to make up for part of the free Sn volatilization loss during smelting preparation by adding more Sn when cutting the material, such as adding 1% to 1.5% more Sn, thereby ensuring that the Sn and Si in the alloy ingot maintain a certain amount. Stoichiometric ratio; at the same time, place the Sn block under the Si particles to prevent the highly fluid Sn from gushing out of the Cu crucible; after reaching complete liquefaction, it lasts for 2 minutes to make the phase distribution more uniform.

In the above step (2), by adjusting the arcing voltage, current intensity and evaporation time, the yield, average particle size and particle size distribution of the composite nanoparticles can be adjusted.

Step (1) Proportioning Sn and Si according to any stoichiometric ratio, such as 20%-60% according to the molar percentage of Sn to Sn and Si.

The purpose of the present invention is to solve the technical problem of preparing Sn-Si alloy nano-composite powder, and provide a preparation technology with simple and easy process route and short synthesis period. The present invention has following characteristics and advantage:

(1) During the process of high-vacuum suspension condensation, the melting power and the number of melting times are adjusted to obtain alloy bulk materials with uniform phase distribution, which is beneficial to the subsequent evaporation and condensation process.

(2) The current methods for preparing nano-Si and Sn materials are still unable to realize the preparation of size-controllable nanoparticles at low cost and high yield, and the preparation of Sn-Si alloy nanocomposite powders has not been reported yet. In the subsequent arc-starting evaporation process of the alloy bulk material, the production rate and particle size of the composite nanopowder can be adjusted by controlling the starting current, voltage and the ratio of hydrogen to inert gas, so that the average particle size can be adjusted within the nanoscale range. control;

In a word, the technical route in the present invention can be used to prepare Sn-Si alloy composite powder with an average particle size in the nanometer scale. The method has a simple process route, a short process, and strong controllability of technical parameters.

Description of drawings

Fig. 1: the phase detection spectrum (X-ray diffraction spectrum) of alloy bulk material in embodiment 1;

Fig. 2: the microtopography figure (scanning electron microscope) of alloy bulk material in embodiment 1;

Fig. 3: the phase detection spectrum (X-ray diffraction spectrum) that prepares the nanocomposite powder in embodiment 1;

Fig. 4: the microtopography figure (scanning electron microscope) that prepares the nanocomposite powder in embodiment 1;

Figure 5: Microscopic appearance and particle size distribution diagram (transmission electron microscope) of the nanocomposite powder prepared in Examples 1 and 2; a ₁ and a ₂ are Example 1, b ₁ and b ₂ are Example 2.

Detailed ways

The present invention will be further described below in conjunction with the examples, but the present invention is not limited to the following examples.

In the examples, the initial Sn block and Si block raw materials were purchased from Beijing Zhongjinyan New Material Co., Ltd., with a purity of 99.9wt% and 99.99wt%, respectively.

Example 1

(1) Firstly, the proportioning is carried out according to the chemical molar ratio Sn:Si=0.34:0.66, and in the high vacuum suspension melting furnace, the Sn block (low melting point, high gasification temperature) is melted by adjusting the power and the power is gradually increased , the corresponding power range is 6 ~ 10kW, which melts the Si block. After the bulk was liquefied, it was suspended for 2 minutes and then cooled.

(2) Use the prepared alloy ingot as the anode, and form a high-intensity arc through discharge under the condition that the volume ratio of hydrogen gas to inert gas is 1:1, the arc starting current is 250A, the arc voltage is 30V, evaporation and condensation After that, Sn-Si particles are formed. The duration of the whole process is 40 minutes, the powder output is nearly 50%, and the Sn-Si material with more Si content remains on the anode.

Example 2

(1) First, carry out the ratio according to the stoichiometric molar ratio Sn:Si=0.3:0.7, and in the high vacuum suspension melting furnace, adjust the power to melt the Sn block (low melting point, high gasification temperature) and gradually increase the power , the corresponding power range is 6 ~ 11kW, making the Si block melt. After the bulk was liquefied, it was suspended for 2 minutes and then cooled.

(2) Use the prepared alloy ingot as the anode, and form a high-intensity arc through discharge under the condition that the volume ratio of hydrogen to inert gas is 1:1, the arc starting current is 100A, the arc voltage is 15V, and evaporation and condensation After that, Sn-Si particles are formed. The duration of the whole process is 40 minutes, the powder output is nearly 40%, and the Sn-Si material with more Si content remains on the anode.

Claims (4)

1. a kind of preparation method of Sn-Si alloy-types nano composite powder, it is characterised in that comprise the following steps：

(1) it is first according to stoichiometric proportion to carry out matching Sn and Si, and in high vacuum suspension smelting furnace, is made by adjusting power Sn blocks melt, and are then gradually increased power, and corresponding power bracket is 6~11kW after increasing power, melts Si blocks；Overall liquid After change, cooled down after suspending 2 minutes and Sn-Si alloy block materials are made；

(2) it is 1 in hydrogen and inert gas argon air volume ratio using the Sn-Si alloy block materials being prepared as anode:1 In the environment of, high intensity electric arc is formed by discharge process, striking current is 100~250A, and arc voltage is 10~30V, is steamed The hair time is 40~60min；Solid-state Sn-Si nano particles are formed after evaporative condenser.

2. in accordance with the method for claim 1, it is characterised in that pass through the Sn of polygamy 1%~1.5% during step (1) blanking Scaling loss amount makes up the free Sn volatilization losses in part when prepared by melting.

3. in accordance with the method for claim 1, it is characterised in that Sn blocks are placed in the lower floor of Si blocks.

4. in accordance with the method for claim 1, it is characterised in that Sn, Si material purity be respectively 99.9wt%, 99.99wt%.