阅读说明：本技术 一种制备纳米SnO2/GC复合负极材料的方法 (Preparation of nano SnO2Method for preparing/GC composite anode material ) 是由 徐桂英 王尚坤 周卫民 王坤 王英新 高占先 安百刚 于 2020-12-31 设计创作，主要内容包括：本发明涉及一种制备纳米SnO-2/GC复合负极材料的方法,其特征在于,包括以下步骤：a)将明胶溶液逐滴加入到锡盐溶液中并搅拌均匀,而后滴加氨水溶液至生成粘稠状白色固体后终止搅拌；b)80±2℃恒温干燥,转移至管式炉炭化热处理,制得目标产物SnO-2/GC复合材料。优点是：采用明胶、锡盐作为原料制备纳米SnO-2/GC复合负极材料,降低了生产成本,简化了生产工艺,获得了较好的循环稳定性和倍率性能,使其能够适用于工业化生产。(The invention relates to a method for preparing nano SnO 2 The method for preparing the/GC composite anode material is characterized by comprising the following steps of: a) dropwise adding the gelatin solution into the tin salt solution, uniformly stirring, dropwise adding the ammonia water solution until a viscous white solid is generated, and stopping stirring; b) drying at 80 + -2 deg.C, transferring to tubular furnace for carbonization heat treatment to obtain targetProduct SnO 2 a/GC composite material. The advantages are that: preparation of nano SnO by using gelatin and tin salt as raw materials 2 the/GC composite negative electrode material reduces the production cost, simplifies the production process, obtains better cycle stability and rate capability, and is suitable for industrial production.)

1. Preparation of nano SnO₂The method for preparing the/GC composite anode material is characterized by comprising the following steps of:

a) dropwise adding the gelatin solution into the tin salt solution, uniformly stirring, dropwise adding the ammonia water solution until a viscous white solid is generated, and stopping stirring;

b) drying at constant temperature of 80 +/-2 ℃, transferring to a tube furnace for carbonization heat treatment to prepare a target product SnO₂a/GC composite material.

2. A method of preparing nano SnO according to claim 1₂The method for preparing the/GC composite negative electrode material is characterized in that gelatin solutions with different volumes are respectively added into a tin salt solution according to the step a) and the step b), and different SnO is obtained by regulating and controlling the mass ratio of tin salt and gelatin in a precursor composite material₂a/GC composite material.

3. A method of preparing nano SnO according to claim 1₂The method for preparing the/GC composite negative electrode material is characterized in that the precipitator is an ammonia water solution.

Technical Field

The invention belongs to the field of lithium ion battery manufacturing, and relates to a method for preparing nano SnO₂A method for compounding a negative electrode material by adopting/GC (gelatin carbon).

Background

With the improvement of the environmental awareness of people, renewable energy gradually replaces the traditional fossil energy. The lithium ion battery is used as important energy storage equipment, has the advantages of high energy density and power density, high voltage and low cost, greatly improves the universality of the lithium ion battery energy storage equipment, and is widely applied to the fields of portable electronic equipment, wearable flexible equipment, electric vehicles, energy storage power grids and the like. The most widely used current negative electrode material is still graphite, however the relatively low theoretical lithium intercalation capacity (372mAh/g) and poor rate capability limit its application in commercial energy storage systems. Therefore, in order to improve the capacity, cycle life and cycle stability of lithium ion batteries, it is important to develop a new anode material.

SnO₂The lithium ion battery cathode material can replace graphite due to the characteristics of high theoretical specific capacity (1492mAh/g), proper lithium-intercalation voltage platform, rich reserve and low price. However, SnO₂The large volume change of the body can cause the pulverization of the crystal lattice collapse material in the charging and discharging process, and the electric conductivity is poor, soUltimately resulting in poor cycling and rate performance. In addition, when pure nano SnO is adopted₂As an electrode material, the material is easily agglomerated into secondary particles with larger sizes under the influence of small particles and large specific surface area, and the electrochemical performance of the material is greatly influenced. To solve this problem, many researchers have prepared SnO with different nanostructures₂And by reducing SnO₂Crystal size and regulation of framework structure to improve SnO₂The electrochemical performance of (2). For example, NaF is used as a morphology control agent in liu et al, and SnO with a directional cone structure is synthesized by a one-step hydrothermal method₂The nanoparticle shell hollow sphere is used as a negative electrode material and still has the reversible capacity of 758mAh/g after being cycled for 100 times under the current density of 0.1A/g. Wang et al prepared octahedral nano SnO by one-step hydrothermal reaction without surfactant₂The porous microspheres with self-assembled structures still have reversible capacity of 690mAh/g after being cycled for 50 times under the current density of 0.5A/g. Although these nano SnO with unique morphological structure₂Can slow down the reduction of capacity, but the SnO can not be fundamentally solved by pure nanocrystallization and shape design₂The mechanical stress caused by the volume change is gradually enhanced along with the increase of the cycle times due to the huge volume change in the cycle process, and finally SnO is caused₂The structure of (2) collapses and electrochemical performance deteriorates. Aiming at the phenomenon, scientific researchers can not only be used as a support framework of a negative electrode structure by utilizing the carbon material with good conductivity and mechanical property, so that the completeness of the electrode structure is prevented from being damaged by stress extrusion, but also the transfer rate of electrons is enhanced by the good conductivity, so that SnO can be effectively improved₂Thus, it is proposed to use SnO₂Preparation of SnO by compounding with carbon material₂Courtel et al, graphite carbon is used as a carbon source, and nano-SnO is synthesized by using an in-situ polyol microwave-assisted technology₂the/C composite material still has the capacity of 370mAh/g after being cycled for 100 circles under the current density of 0.2A/g. Such SnO₂The-carbon recombination method indeed improves SnO₂The lithium ion battery negative electrode material has capacity and cycle stability, but has a tendency of capacity reduction in the long-term cycle process, and is composed ofThe synthesis technology is complex and tedious, and is difficult to be practically applied in industrial production. To ensure SnO₂The industrial production of the/carbon composite cathode material in the lithium ion battery must be adhered to improve SnO with low cost and high efficiency₂The electrochemical performance of (2). Therefore, there is an urgent need for a low-cost and easy-to-operate SnO₂A method for preparing the/C composite material.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a method for preparing nano SnO₂The method for the/GC composite cathode material reduces the production cost, simplifies the process and improves the cycle stability and the rate capability of the lithium ion battery cathode material.

In order to achieve the purpose, the invention is realized by the following technical scheme:

preparation of nano SnO₂The method for preparing the/GC composite anode material is characterized by comprising the following steps of:

a) dropwise adding the gelatin solution into the tin salt solution, uniformly stirring, dropwise adding the ammonia water solution until a viscous white solid is generated, and stopping stirring;

b) drying at constant temperature of 80 +/-2 ℃, transferring to a tube furnace for carbonization heat treatment to prepare a target product SnO₂a/GC composite material.

Respectively adding gelatin solutions with different volumes into the tin salt solution according to the step a) and the step b), and regulating and controlling the mass ratio of the tin salt to the gelatin in the precursor composite material to obtain different SnO₂a/GC composite material.

The precipitant is ammonia water solution.

Compared with the prior art, the invention has the beneficial effects that:

the invention adopts gelatin and tin salt as raw materials to prepare nano SnO₂the/GC composite negative electrode material reduces the production cost, simplifies the production process, obtains better cycle stability and rate capability, and is suitable for industrial production. Gelatin is a linear polypeptide compound consisting of 18 amino acids, has the characteristics of low price, good biocompatibility and easy commercialization, and is combined with most of the gelatinThe materials have stronger physical and chemical effects, and the synthesized material has better flexibility and mechanical property. The invention adopts the sol-gel method which can be amplified in the laboratory to prepare the composite material, the method has simple working procedure and convenient operation, and the prepared nano SnO with a small amount of mesopores₂The gelatin-carbon composite material has better circulation stability and rate capability, greatly improves the electrochemical performance of the material, and is also suitable for other metal oxides by using the Sol-Gel method for coating by using gelatin as a carbon source.

Drawings

FIG. 1 is a process flow diagram of the first embodiment.

FIG. 2 shows GC (gelatin carbon) and SnO₂And SnO in different mass ratios₂XRD pattern of/GC (gelatin carbon) composite.

In FIG. 3, (a) to (c) are SnO, respectively₂/GC-15、SnO₂(ii) GC-40 and SnO₂TG/DTG plot of/GC-90 composite; in FIG. 3, (d) is SnO₂/GC-15、SnO₂(ii) GC-40 and SnO₂Summary of the composite TG/GC-90.

In FIG. 4, (a) and (b) are nano SnO₂SEM images of the particles; in FIG. 4, (c) and (d) are SnO₂SEM image of/GC-40 composite material.

In FIG. 5 (a) is SnO₂SEM image of/GC-40 composite material; in FIG. 5, (b) to (f) are SnO₂EDS scanning of C, N, O, Sn element and surface element semi-quantitative analysis chart of the composite material of the/GC-40.

In FIG. 6, (a) is SnO₂XPS survey of the/GC-40 composite; (b) XPS fine spectrum of C1 s; (c) XPS fine spectrum of Sn3 d; (d) XPS Fine Spectrum (SnO) of N1s₂/GC-40)。

FIG. 7 shows that the BJH method calculates SnO₂/GC-15、SnO₂(ii) GC-40 and SnO₂Pore size distribution curve diagram of the/GC-90 composite material; fig. 7 (a) is an overall graph; fig. 7 (b) is a partial graph.

FIG. 8(a) is SnO at a current density of 0.1A/g₂、GC、SnO₂/GC-15、SnO₂(ii) GC-40 and SnO₂A cycle capacity plot for the/GC-90 composite; (b) is at 0.1A/g,0.2A/g,0.5A/g,1A/g,2A/g and 0.1A/gSnO at flow Density₂、SnO₂/GC-15、SnO₂(ii) GC-40 and SnO₂Magnification diagram of the/GC-90 composite material, (c) is SnO at a current density of 0.1A/g₂Long cycle capacity plot of the/GC-40 composite.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings, but it should be noted that the present invention is not limited to the following embodiments.

Preparation of nano SnO₂The method for preparing the/GC composite anode material comprises the following steps:

1.SnO₂preparation of nanospheres

a, dropwise adding a precipitator into a tin salt solution until the pH value of the solution is 6 to obtain milky precipitate, and centrifugally washing for multiple times to obtain SnO₂The precursor solid powder of (4);

b, after drying treatment, carbonizing for 3 hours in an air atmosphere at 500 ℃, cooling, collecting a sample, and sealing and storing;

2.SnO₂preparation of a/GC composite

a, dropwise adding a gelatin solution into a tin salt solution, uniformly stirring, dropwise adding an ammonia water solution until a viscous white solid is generated, and stopping stirring;

b drying at the constant temperature of 80 +/-2 ℃, transferring to a tubular furnace for carbonization heat treatment to prepare a target product SnO₂a/GC composite material.

c, according to the step a and the step b, gelatin solutions with different volumes are respectively added into the tin salt solution, and different SnO is obtained by regulating and controlling the mass ratio of the tin salt and the gelatin in the precursor composite material₂a/GC composite material.

Example one

(1)SnO₂Preparation of nanospheres

Adding 10mmol SnCl₄·5H₂Dissolving O (0.3506g) in 40mL of deionized water to obtain a solution A, then dropwise adding 4mol/L ammonia water solution while stirring until the pH of the solution is about 6, continuously stirring for 1 hour to obtain a milky white precipitate, and respectively centrifugally cleaning with deionized water and absolute ethyl alcohol for three times to obtain SnO₂And (3) nanoparticles. Drying at 80 deg.C of 12h later, carbonizing for 3h in 500 ℃ air atmosphere, cooling and collecting SnO₂And (4) sealing and storing the nanoparticles.

(2)SnO₂Preparation of a/GC composite

Dissolving 10g of gelatin in 100ml of deionized water, magnetically stirring for 1h to fully swell gelatin particles, transferring the gelatin particles to a water bath, and magnetically stirring at 80 ℃ to obtain a light yellow gelatin solution B. Then 10mmol SnCl₄·5H₂Dissolving O (0.3506g) in 40mL of deionized water, obtaining colorless and clear tin salt solution C after 1h, respectively dropwise adding 15mL, 40mL and 90mL of gelatin B into the solution C, fully stirring for 30 minutes, then dropwise adding 4mol/L ammonia water solution until the pH of the solution is about 7, stirring at the constant temperature of 60 ℃ until the solution is milky viscous liquid, stopping heating, and cooling to obtain gelatinous white solid. Drying at 80 deg.C for 16h, grinding into powder, transferring into crucible, and placing in tube furnace N₂Heating at 500 deg.C for 3h in atmosphere, and cooling to room temperature to obtain SnO₂the/GC composite material is named SnO according to the volume amount of dropwise added gelatin₂/GC-15、SnO₂/GC-40、SnO₂and/GC-90. For comparison, the cooled gelatin solution was also subjected to the same drying and carbonization treatments, and the obtained gelatin carbon sample was named GC. Finally, the lithium ion battery cathode material is used as a lithium ion battery cathode material to assemble a button battery and the electrochemical performance of the button battery is tested.

FIG. 2 shows GC (gelatin carbon) and SnO₂And SnO in different mass ratios₂XRD pattern of/GC (gelatin carbon) composite. SnO₂The lattice parameters corresponding to the diffraction peaks are respectivelyP42/mnm space group, and has four strong diffraction peaks at 2 theta of 27 degrees, 34 degrees, 38 degrees and 52 degrees, corresponding to SnO₂The (110), (101), (200) and (211) crystal planes of (A) and (B), which are similar to those of SnO with a tetragonal rutile structure₂Standard card consensus (ICOD 01-077-. But in SnO₂No SnO was observed in XRD pattern of/GC composite material₂May be such that SnO is not formed in the composite material₂And another result may be compoundingSnO is generated in the material₂However, SnO₂Is amorphous and therefore does not show characteristic peaks.

From FIG. 3(d), SnO₂/GC-15、SnO₂(ii) GC-40 and SnO₂The carbon content in the/GC-90 composite was 62.0%, 68.2% and 74.2%, respectively.

As shown in FIG. 4(a), nano SnO with an amplification of 10KX₂The particles are significantly agglomerated into large clusters. SnO for more intuitive observation₂Has a microstructure of 50KX SnO₂The SEM image shows that the nano SnO₂The particles are spherical, and the particle size range is 10-20 nm. Furthermore, as shown in FIGS. 4(c) and (d), it is shown that SnO is more simple than SnO₂Spherical nano particles, the micro appearance of the composite material is greatly changed, SnO₂Is completely wrapped by gelatin, has irregular block structure and smooth surface

As can be seen from FIG. 5, the signals of carbon element in gelatin and oxygen and tin element from tin dioxide are uniformly overlapped on the whole particle surface, which shows that the carbon layer is uniformly coated on SnO₂The surface of the nanoparticles. The semi-quantitative analysis of each element is shown in table 1.

TABLE 1 semi-quantitative analysis table for each element of Map

As shown in FIG. 6(a), SnO₂the/GC-40 composite material contains four elements of Sn, O, C and N. FIGS. 6(b) - (d) are XPS high resolution fine spectra of Sn3d, C1s and N1s, respectively, and it is clear from the Sn3d spectrum of FIG. 6(b) that the bond energies of Sn3d5/2 and Sn3d3/2 are 487.02eV and 495.45eV, respectively, and the difference in bond energy between them is 8.47eV, and SnO₂The peak value of the spin orbit is consistent, and the Sn element is proved to be Sn⁴⁺In ionic form. FIG. 6(C) shows the C1s peak splitting into four types of carbon, the peak at 284.66eV belonging to sp of the C-C single bond²Graphitic hybrid carbon, the peak at 285.65eV belonging to the sp of a C-O single bond³Diamond-like hybrid carbon, peaks at 287.8eV and 288.95eV correspond to carbon with C ═ O bonds and C — O bonds, respectively. The high resolution N1s peak of figure 6(d) has four components,their binding energies were 398.64eV, 400.0eV, 401.07eV, and 403.22eV, respectively, which correspond to 42.45 wt% of pyridine nitrogen, 13.77 wt% of nitro nitrogen, 26.72 wt% of pyrrole nitrogen, and 17.06 wt% of tetravalent nitrogen, respectively, and it was found that the main forms of nitrogen existing in the carbon layer were pyridine nitrogen and pyrrole nitrogen.

As shown in FIG. 7, SnO₂-GC-15、SnO₂-GC-40 and SnO₂The specific surface areas of the GC-90 samples were 4.879²/g、34.567m²G and 2.642m²The pore size distribution is mostly concentrated between 3 and 12nm, indicating SnO₂Most of samples obtained by mixing with the gelatin have mesoporous structures, which are related to the physicochemical properties of the gelatin.

Referring to FIG. 8(a), GC and SnO were observed after charging and discharging 100 times₂The lithium storage capacities of the lithium batteries are respectively 111.9mAh/g and 57.8mAh/g, and SnO₂-GC-15、SnO₂-GC-40 and SnO₂The lithium storage capacity of the GC-90 samples was 321.9mAh/g, 353.6mAh/g and 307.9mAh/g, respectively. Comparison found SnO₂Lithium storage capacity ratio of/GC composite material of pure GC and SnO₂The carbon coating can effectively relieve SnO₂Structural stress generated by huge volume change in the charge-discharge cycle process stabilizes the lattice structure of the material and hinders the collapse of the lattice structure. See FIG. 8(b), SnO after 100 cycles at current densities of 0.1A/g,0.2A/g,0.5A/g,1A/g,2A/g, respectively₂The lithium storage capacity performance of the/GC-40 is best shown as 379.2mAh/g, 298.3mAh/g, 206.8mAh/g, 135.3mAh/g and 61.1mAh/g, and when the current density returns to 0.1A/g again, SnO₂the/GC-40 still has a lithium storage capacity of 385.3 mAh/g. While SnO₂、SnO₂/GC-15、SnO₂The results of the lithium storage capacities shown by/GC-90 were 50.5mAh/g, 274.6mAh/g, and 322.6mAh/g, respectively, and they showed that SnO₂Relative to SnO in/GC-40₂、SnO₂(ii) GC-15 and SnO₂the/GC-90 has better rate performance. FIG. 8(c) is SnO after 500 cycles of charge-discharge cycle₂the/GC-40 sample still had a lithium storage capacity of 397mAh/g, which further indicates that SnO₂the/GC-40 composite material has excellent electrochemical stability. Simultaneously, SnO is increased along with the increase of the number of cycles₂/GC-The lithium storage capacity of the 40 samples decreased first and then increased.

The invention takes GC as a carbon source and adopts a one-pot Sol-Gel (Sol-Gel) method to treat nano SnO₂Carrying out carbon coating in-situ to generate a tin salt/GC composite precursor, and then carrying out high-temperature calcination to obtain porous SnO₂a/GC composite material. Meanwhile, the electrochemical performance of the composite material is further optimized by regulating and controlling the mass ratio of tin salt to GC in the precursor composite material.