Lithium ion battery nanocomposite negative electrode material and preparation method thereof

Abstract

The application belongs to the technical field of lithium ion batteries, and specifically discloses a kind of lithium ion battery nano composite negative electrode material and its preparation method, with glucosamine hydrochloride as amorphous carbon source, GO and SnCl2 as raw material, SnO2@C-NH2 / rGO nano composite material is prepared by one-step hydrothermal method, the introduction of amino functional group can further enhance the interaction between SnO2 particles and amorphous carbon layer, make the growth of SnO2 grain be further inhibited, and help to firmly anchor SnO2 nanoparticles on the surface of rGO sheet layer;At the same time, the nitrogen doping of carbon structure not only improves the conductivity of the whole material, but also provides more active sites for Li + deintercalation;Therefore, the capacity of SnO2@C-NH2 / rGO prepared by the application is 810mAh / g after 75 cycles, which shows that the lithium ion battery nano composite negative electrode material prepared by the application has good electrochemical cycle performance.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a lithium-ion battery nanocomposite anode material and its preparation method. Background Technology

[0002] Lithium-ion batteries possess characteristics such as high voltage, high energy density, environmental friendliness, rechargeability, and long lifespan, making them widely used in mobile phones, small digital devices, electric vehicles, and other fields. They are currently a key research focus in the global new energy research field. At present, graphite is the primary anode material for lithium-ion batteries, but its relatively low capacity (372 mAh·g) is a concern. -1 This cannot meet the development needs of high-energy-density batteries.

[0003] The theoretical capacity of SnO2 metal oxide as a negative electrode material for lithium-ion batteries is 782 mAh·g. -1 It has a capacity far exceeding that of graphite, and its natural reserves are relatively abundant, inexpensive, and easy to prepare, making it a very promising electrode material. In particular, when combined with two-dimensional graphene materials, it can further enhance the conductivity of the electrode material, improve the lithium insertion / extraction capability of the material, and extend the cycle life of the electrode material.

[0004] Currently, the preparation of SnO2 / graphene composite materials mainly adopts chemical methods, for two main reasons: First, the chemical preparation process is relatively simple, the synthesis cost is low, and it is suitable for mass production; Second, the preparation of graphene composite materials often uses graphene oxide prepared by the Hummers method as a precursor. Graphene oxide has a large number of oxygen-containing functional groups, which can easily load nanoparticles onto its surface. Numerous reports on SnO2 / graphene composite materials exist in existing literature. For example, the literature "Adv. Mater., 2013, 25, 2152-2157" reports the preparation of SnO2 nanoparticles using SnCl4·5H2O as a raw material. First, SnO2 nanoparticles are prepared by hydrothermal reaction at 120℃ for 28 h. Then, the SnO2 nanoparticles are mixed with an aqueous solution of graphene oxide, and the reaction is continued at 120℃ for 2 h using hydrazine hydrate as a reducing agent to obtain the SnO2 / graphene composite material. The literature "Adv. Funct. Mater., 2012, 22, 1647-1654" reports the preparation of SnO2 / graphene composite materials using atomic layer deposition technology. A method for preparing SnO2 / graphene composite materials offers precise control over the crystal morphology of SnO2 nanoparticles; however, the preparation process requires specialized equipment, increasing costs. Patent CN201410792374.1, "Nano-SnO2 / Graphene Composite Material for Lithium-ion Batteries and its Preparation Method," provides a two-step method: first, SnO2 nanoparticles are prepared; then, the SnO2 nanoparticles are mixed with a graphene oxide solution, and excess SnCl2 is used to reduce the graphene oxide, resulting in the SnO2 / graphene composite material. This method avoids the use of highly toxic hydrazine hydrate as a reducing agent, but the preparation process remains relatively complex. Therefore, developing a simple and rapid method for preparing SnO2 / graphene composite electrode materials is of great significance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a lithium-ion battery nanocomposite anode material and its preparation method.

[0006] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0007] The first objective of this invention is to provide a method for preparing a lithium-ion battery nanocomposite anode material, comprising the following steps:

[0008] S1. Weigh 0.5g SnCl2·2H2O and dissolve it in 0.5mL of concentrated hydrochloric acid solution. Stir magnetically for 30min until SnCl2 is completely dissolved to form SnCl2 acid solution.

[0009] S2. Weigh 0.2837g of glucosamine hydrochloride and dissolve it in 20mL of deionized water. Stir magnetically for 30min until the glucosamine hydrochloride is completely dissolved. Add SnCl2 acid solution dropwise to 20mL of glucose solution to obtain a mixed solution of SnCl2 and glucosamine hydrochloride.

[0010] S3. Take 5 mg / mL of GO solution and disperse it by ultrasonication. Add the mixed solution of SnCl2 and glucosamine hydrochloride to 100 mL of GO solution and stir for 30 min until uniform. Transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner and react it at 170℃ for 2 h.

[0011] S4. Take the product after the hydrothermal reaction, wash it with deionized water until neutral by centrifugation, and freeze-dry the precipitate for 24 hours to obtain SnO2@C-NH2 / rGO nanocomposite anode material.

[0012] Furthermore, the concentration of concentrated hydrochloric acid in step S1 is 36% to 38%.

[0013] Furthermore, the preparation process of the GO solution in step S3 is as follows:

[0014] First, add 96 mL of concentrated sulfuric acid to an Erlenmeyer flask and place it in an ice bath for 10 minutes. Once the flask is completely cooled, place it on a magnetic stirrer and stir slowly. Then, weigh 2.0 g of sodium nitrate and add it to the Erlenmeyer flask and stir. After 30 minutes, add 2 g of flake graphite, followed by 12 g of potassium permanganate slowly after 10 minutes. Place the entire system in an ice bath and react for 1 hour. Immediately afterwards, transfer the Erlenmeyer flask to a 35°C water bath and react for 2 hours. Then, slowly add 80 mL of water and set the water bath temperature to 90°C. At 6℃, wait until the temperature reaches 96℃, wait 30 minutes, then add 200mL of water, followed by 10mL of hydrogen peroxide. The reaction system changes from bright yellow to brownish-yellow. After waiting 10 minutes, pour the solution from the conical flask into a centrifuge cup and centrifuge while hot for 5 minutes. Then, use 57mL of concentrated hydrochloric acid to prepare 500mL of hydrochloric acid for two acid washes, and wash with water until neutral. Finally, prepare 500mL of the obtained colloidal solution and place it in an ultrasonic disperser for sonication for 45 minutes to obtain a 5mg / m³ GO solution.

[0015] Preferably, the size of the flake graphite is 400 mesh.

[0016] The second objective of this invention is to provide a lithium-ion battery nanocomposite anode material prepared using the above method.

[0017] Compared with existing technologies, this invention uses glucosamine hydrochloride as an amorphous carbon source and GO and SnCl2 as raw materials to prepare SnO2@C-NH2 / rGO nanocomposite materials via a one-step hydrothermal method. The introduction of amino functional groups can further enhance the interaction between SnO2 particles and the amorphous carbon layer, further inhibiting the growth of SnO2 grains and helping to firmly anchor SnO2 nanoparticles to the surface of rGO sheets. Simultaneously, nitrogen doping of the carbon structure not only improves the overall conductivity of the material but also provides a basis for Li… + The insertion and extraction of SnO2 provides more active sites; therefore, the SnO2@C-NH2 / rGO prepared in this invention has a capacity of 810 mAh / g after 75 cycles, indicating that the lithium-ion battery nanocomposite anode material prepared in this invention has good electrochemical cycling performance. Attached Figure Description

[0018] Figure 1 The image shows the FTIR spectrum of the prepared SnO2@C-NH2 / rGO nanocomposite anode material.

[0019] Figure 2 The XRD pattern of the prepared SnO2@C-NH2 / rGO nanocomposite anode material is shown.

[0020] Figure 3 TEM image of the prepared SnO2@C-NH2 / rGO nanocomposite anode material.

[0021] Figure 4 The results of EDX mapping analysis of the prepared SnO2@C-NH2 / rGO nanocomposite anode material are shown.

[0022] Figure 5 The photoelectron spectroscopy spectra of the prepared SnO2@C-NH2 / rGO nanocomposite anode material are shown in Figure 1: a is the O1s photoelectron spectrum of SnO2@C-NH2 / rGO; b is the N1s photoelectron spectrum of SnO2@C-NH2 / rGO.

[0023] Figure 6 The first three cycles of CV curves and constant current charge-discharge curves of the prepared SnO2@C-NH2 / rGO nanocomposite anode material are shown: (a) is the first three cycles of CV curves; (b) is the constant current charge-discharge curve.

[0024] Figure 7 Cycling curves and rate performance of the prepared SnO2@C-NH2 / rGO nanocomposite anode material at a current density of 0.1C: (a) Cycling curve; (b) Rate performance. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0026] 1) Weigh 0.5g SnCl2·2H2O and dissolve it in 0.5mL of concentrated hydrochloric acid solution (concentration is 36%), and stir magnetically for 30min until SnCl2 is completely dissolved to form SnCl2 acid solution;

[0027] 2) Weigh 0.2837g of glucosamine hydrochloride and dissolve it in 20mL of deionized water. Stir magnetically for 30min until the glucosamine hydrochloride is completely dissolved. Add SnCl2 acid solution dropwise to 20mL of glucose solution to obtain a mixed solution of SnCl2 and glucosamine hydrochloride.

[0028] 3) First, add 96 mL of concentrated sulfuric acid to an Erlenmeyer flask and place it in an ice bath for 10 minutes. Once completely cooled, place it on a magnetic stirrer and stir slowly. Then, weigh 2.0 g of sodium nitrate and add it to the Erlenmeyer flask. After 30 minutes, add 2 g of flake graphite (400 mesh), followed by 12 g of potassium permanganate after 10 minutes. Place the entire system in an ice bath and react for 1 hour. Next, transfer the Erlenmeyer flask to a 35°C water bath and react for 2 hours. Slowly add 80 mL of water and set the water bath temperature to 96°C. Once the temperature reaches 96°C, wait 30 minutes and then add 200 mL of water, followed by 10 mL of hydrogen peroxide. The reaction mixture... The solution changed from bright yellow to brownish-yellow. After waiting for 10 minutes, the solution in the conical flask was poured into a centrifuge cup and centrifuged while hot for 5 minutes. Then, 57 mL of concentrated hydrochloric acid was used to prepare 500 mL of hydrochloric acid for two acid washes, followed by washing with water until neutral. Finally, the obtained colloidal solution was prepared into 500 mL and placed in an ultrasonic disperser for 45 minutes to obtain a 5 mg / mL GO solution. Then, the 5 mg / mL GO solution was ultrasonically dispersed, and a mixed solution of SnCl2 and glucosamine hydrochloride was added to 100 mL of GO solution. The mixture was stirred for 30 minutes until homogeneous, and then transferred to a hydrothermal reactor with a polytetrafluoroethylene liner. The reaction was carried out at 170°C for 2 hours.

[0029] 4) Take the product after the hydrothermal reaction, wash it with deionized water until neutral, freeze-dry the precipitate for 24 hours to obtain SnO2@C-NH2 / rGO nanocomposite anode material.

[0030] The SnO2@C-NH2 / rGO nanocomposite anode material prepared in the above examples was subjected to structural testing and characterization.

[0031] Figure 1 The FTIR curves for SnO2@C-NH2 / rGO are shown. Figure 1It can be seen that SnO2@C-NH2 / rGO at 3460, 1640, 1390, 1100, and 620 cm⁻¹ -1 There is a clearly broad characteristic absorption peak at 3460 cm⁻¹. -1 The peak for the stretching vibration of OH is 1640 cm⁻¹. -1 The vibrations are the stretching vibrations of C=C and the bending vibrations of the OH groups of adsorbed water molecules, while 1390, 1100 and 620 cm⁻¹ are the values ​​of these vibrations. -1 The peaks at these locations correspond to the deformation vibration of OH, the CO vibration of C-OH, and the out-of-plane bending vibration of OH, respectively. Meanwhile, SnO2@C-NH2 / rGO shows a peak at 1640 cm⁻¹. -1 and 1390cm -1 The characteristic peaks at 1100 and 620 cm⁻¹ are stronger, mainly due to the association of the NH vibration and C=C stretching vibration of the amide bond in SnO₂@C-NH₂ / rGO. This successfully demonstrates the introduction of amino groups into the SnO₂@C-NH₂ / rGO composite material. SnO₂@C-NH₂ / rGO exhibits stronger characteristic peaks at 1100 and 620 cm⁻¹. -1 The characteristic absorption peak at that point shifts slightly to lower wavelengths, indicating that SnO2@C-NH2 / rGO generates more intermolecular hydrogen bonds / CO-Sn bonds. Figure 2 The XRD pattern of SnO2@C-NH2 / rGO is shown. rGO exhibits a broad (002) diffraction peak at 2θ = 24.07° and a weak (101) diffraction peak at 2θ = 43.65°. SnO2 / C-NH2@rGO shows strong diffraction peaks at 2θ = 26.58°, 33.68°, and 51.73°, corresponding to the (110), (101), and (211) crystal planes of SnO2, respectively. It also shows two weaker diffraction peaks at 2θ = 38.13° and 65.63°, corresponding to the (111) and (301) crystal planes of SnO2, respectively. The average grain size of SnO2 in SnO2 / C-NH2@rGO is calculated to be 2.9 nm using the Scherrer equation. In the SnO2 / C-NH2@rGO sample, the encapsulation effect of amorphous carbon inhibits the coarsening of SnO2 particles, and the introduction of amino groups can further enhance the interaction between SnO2 grains and amorphous carbon layers, further restricting the growth of SnO2 grains.

[0032] Figure 3 TEM image of SnO2@C-NH2 / rGO. Figure 3 As can be clearly seen in image c, countless 2-3 nm SnO2 nanoparticles are uniformly distributed on the rGO sheets. Further magnification... Figure 3In image d, the interplanar spacings of SnO2 were observed to be 0.33 nm and 0.26 nm, respectively, which are in good agreement with the (110) and (101) lattice planes of SnO2, consistent with the XRD results. Further EDX mapping analysis was performed on the TEM images of the SnO2@C-NH2 / rGO sample, as shown... Figure 4 As shown, Sn, C, O and N elements are clearly distributed uniformly on the surface of the material, indicating that nitrogen-containing functional groups were successfully introduced into the sample after the hydrothermal reaction of glucosamine hydrochloride.

[0033] To further understand the elemental composition and valence states in SnO2@C-NH2 / rGO, photoelectron spectroscopy analysis was performed on the C, N, O, and Sn elements in SnO2@C-NH2 / rGO. Figure 5 The photoelectron spectroscopy spectrum of SnO2@C-NH2 / rGO is shown. Figure 5 a shows that the O1s in SnO2@CNH2 / rGO has three fitted peaks at 531.3 eV, 532.5 eV and 533.6 eV, corresponding to the bonds of C=O / Sn-O-Sn, CO / CO-Sn and C-OH, respectively. Figure 5 The N1s spectrum in b belongs to SnO2@CNH2 / rGO, mainly exhibiting two fitting peaks located at 400.5 eV and 402.3 eV, corresponding to pyridine N (400.3-400.5 eV) and N oxide [102-103]. XPS analysis showed that the N content in SnO2@C-NH2 / rGO was 2.25%. These results indicate that the amino functional group successfully entered SnO2@C-NH2 / rGO after the hydrothermal reaction, improving the overall material conductivity and providing a suitable environment for Li... + The insertion and extraction processes provide more active sites.

[0034] like Figure 6 Figure a shows the cyclic voltammetry (CV) curves of SnO2@C-NH2 / rGO in the range of 0–3 V at a scan rate of 0.1 mV / s. The CV curves of SnO2@C-NH2 / rGO maintain the obvious redox peaks of SnO2-based materials. Through cathode scanning, SnO2@C-NH2 / rGO exhibits two reduction peaks at 0.12 V and 0.9 V, while anodic scanning shows two oxidation peaks at 0.56 V and 1.27 V. The sharp reduction peak at 0.12 V and the oxidation peak at 0.56 V mainly correspond to the lithiation reaction of Sn and the dealloying reaction of Li4.4Sn. The two redox peaks at 0.9V and 1.27V are due to two main factors: firstly, the formation of an SEI film during charging and discharging; and secondly, the conversion reaction between SnO2 and Li2O. Throughout the scanning process, the overall curves were found to be largely overlapping, indicating that the SnO2@C-NH2 / rGO material exhibits good electrochemical reversibility.

[0035] like Figure 6 In step b, the initial discharge capacity of SnO2@C-NH2 / rGO was 1589 mAh / g, and the second discharge capacity was 1150 mAh / g, with an initial coulombic efficiency as high as 72.3%. The irreversible capacity of SnO2@C-NH2 / rGO in the first cycle mainly comes from the formation of Li2O and the SEI film. The BET pore size analysis above shows that in the electrochemical reaction of SnO2@C-NH2 / rGO during charge and discharge, the contact area between SnO2@C-NH2 / rGO and the electrolyte is small. This results in a corresponding reduction in the electrolyte consumed during the formation of the SEI film, thus improving the overall initial coulombic efficiency of SnO2@C-NH2 / rGO.

[0036] like Figure 7 As shown in Figure a, the discharge capacities of SnO2@C-NH2 / rGO at the 25th, 50th, and 75th cycles were 920 mAh / g, 877 mAh / g, and 810 mAh / g, respectively, with the discharge specific capacity remaining above 800 mAh / g, indicating good electrochemical stability. Figure 7 Figure b shows the rate performance of SnO2@C-NH2 / rGO at 0.1C, 0.2C, 0.5C, 1C, and 5C. SnO2@C-NH2 / rGO maintains a capacity of 900 mAh / g at a current density of 0.1C. When the current density increases to 1C and 5C, the capacity remains around 558 mAh / g and 408 mAh / g, respectively. When the current density returns to 0.1C, SnO2@C-NH2 / rGO can recover to around 761 mAh / g. This indicates that the SnO2@C-NH2 / rGO composite electrode exhibits good cycle stability.

[0037] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preparing a lithium-ion battery nanocomposite anode material, characterized in that, Includes the following steps: S1. Weigh 0.5g SnCl2·2H2O and dissolve it in 0.5mL of concentrated hydrochloric acid solution. Stir magnetically for 30min until SnCl2 is completely dissolved to form SnCl2 acid solution. S2. Weigh 0.2837g of glucosamine hydrochloride and dissolve it in 20mL of deionized water. Stir magnetically for 30min until the glucosamine hydrochloride is completely dissolved. Add SnCl2 acid solution dropwise to 20mL of glucosamine hydrochloride solution to obtain a mixed solution of SnCl2 and glucosamine hydrochloride. S3. Take 5 mg / mL of GO solution and disperse it ultrasonically. Add the mixed solution of SnCl2 and glucosamine hydrochloride to 100 mL of GO solution and stir for 30 min until homogeneous. Transfer it to a hydrothermal reactor with a polytetrafluoroethylene liner and react it hydrothermally at 170℃ for 2 h. The preparation process of GO solution is as follows: First, add 96 mL of concentrated sulfuric acid to an Erlenmeyer flask and place it in an ice bath for 10 min. After it has completely cooled, place it on a magnetic stirrer and stir slowly. Then, weigh 2.0 g of sodium nitrate and add it to the Erlenmeyer flask and stir. After 30 min, add 2 g of flake graphite, followed by 12 g of potassium permanganate after 10 min. Place the entire system in an ice bath and react for 1 h. Next, transfer the Erlenmeyer flask to a 35°C water bath and react for 2 h. Then, slowly add 80 mL of water and set the water bath temperature to 96°C. After the temperature reaches 96°C, wait 30 min and then add 200 mL of water, followed by 10 mL of hydrogen peroxide. The reaction system changes from bright yellow to brownish-yellow. After 10 min, pour the solution from the Erlenmeyer flask into a centrifuge cup and centrifuge while hot for 5 min. Then, prepare 500 mL of hydrochloric acid with 57 mL of concentrated hydrochloric acid and perform two acid washes, followed by washing with water until neutral. Finally, prepare 500 mL of the resulting colloidal solution and sonicate it in an ultrasonic disperser for 45 min. A GO solution with a concentration of 5 mg / mL was obtained; S4. Take the product after the hydrothermal reaction, wash it with deionized water until neutral by centrifugation, and freeze-dry the precipitate for 24 hours to obtain SnO2@C-NH2 / rGO nanocomposite anode material.

2. The method for preparing the lithium-ion battery nanocomposite anode material according to claim 1, characterized in that, The concentration of concentrated hydrochloric acid in step S1 is 36%~38%.

3. The method for preparing the lithium-ion battery nanocomposite anode material according to claim 1, characterized in that, The size of the flake graphite is 400 mesh.

4. A lithium-ion battery nanocomposite anode material prepared by the method according to any one of claims 1-3.

Images