Preparation and application of a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material

Abstract

This invention belongs to the field of battery anode material technology, and discloses the preparation and application of a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material. The invention involves treating a bismuth precursor using a liquid reduction method to obtain porous elemental bismuth; then dispersing the porous elemental bismuth into a system containing a carbon matrix precursor to form a uniform and stable dispersion, followed by freeze-drying to obtain a mixed aerogel; calcining the mixed aerogel under a protective atmosphere to obtain a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material. This invention features a simple process, low raw material cost, high controllability of operation steps, and can be mass-produced. The product obtained by this invention has a novel structure; the bismuth nanospheres embedded in the two-dimensional carbon matrix sheet are small and uniformly dispersed, exhibiting high reactivity. When used as an anode material for lithium-ion batteries and / or sodium-ion batteries and / or potassium-ion batteries, it possesses high specific capacity, long cycle life, and excellent rate performance.

Description

Technical Field

[0001] This invention belongs to the field of battery anode material technology, and specifically relates to the preparation and application of a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material. Background Technology

[0002] Bismuth (Bi), as a representative alloy material, possesses a suitable redox potential (Bi... 3+ / Bi=0.308V vs. SHE), lower thermal conductivity, higher electrical conductivity (7.8×10⁻⁶). 5 S m -1 High theoretical specific capacity (385mAh g) -1 ) and volumetric energy density (3800 mAh cm⁻¹) -3 Bi possesses numerous advantages, with a volumetric capacity exceeding that of any currently reported anode material. Furthermore, Bi belongs to the hexagonal crystal system, and its large interlayer spacing along the c-axis (d(003) = 0.395 nm) facilitates the diffusion of Li, Na, and K ions. These combined advantages make metallic Bi-based materials a very promising anode material for lithium, sodium, and potassium-ion batteries. However, Bi undergoes significant structural changes during charge and discharge, such as a 250% volume expansion rate in the fully sodium-intercalated state and a 409% volume expansion rate in the fully potassium-intercalated state. This can lead to structural cracking or even pulverization of Bi-based materials, resulting in loss of electrochemical activity. Constructing composite materials from nanostructured Bi with a carbon matrix is ​​currently the most common method to improve the lithium, sodium, and potassium storage performance of Bi-based materials.

[0003] Although some positive progress has been made in constructing Bi / C composite materials to improve sodium and potassium storage performance (Journal of Alloys and Compounds, 2023, 935: 168207. Small, 2022, 18(44): 2204045), the lithium, sodium, and potassium storage performance of Bi-based materials needs further improvement. This is because lithium, sodium, and potassium ion batteries are and will be used in high-power energy storage devices in fields such as energy storage power stations, smart grids, and electric vehicles. This requires lithium, sodium, and potassium ion batteries to operate at ultra-high current densities (e.g., 10 Ag). -1The lithium, sodium, and potassium storage performance of Bi / C composites is mainly limited by the low Bi content, which hinders high capacity, and the large Bi size, which prevents faster electrochemical reaction kinetics to improve rate performance. Therefore, further reducing the nanoscale size of Bi (~10 nm) and increasing the Bi content (>90 wt%) in Bi / C composites while ensuring effective carbon coating is crucial for improving the sodium and potassium storage performance of Bi-based materials. Currently reported nanomaterial synthesis methods cannot simultaneously meet the requirements of ultra-small Bi size, ultra-high Bi content, and efficient carbon coating in Bi / C composites. New nanomaterial synthesis methods need to be developed to simultaneously meet these structural requirements in order to further improve the lithium, sodium, and potassium storage performance of Bi-based materials. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a method for preparing a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material.

[0005] This invention employs a novel method for synthesizing nanomaterials based on the capillary forces of nanopores, and synthesizes a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material.

[0006] Another objective of this invention is to provide a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material prepared by the above method.

[0007] Another objective of this invention is to provide the application of the above-mentioned two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material in ion batteries.

[0008] The two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material prepared in this invention has the characteristics of high specific capacity, long cycle life and excellent rate performance when used as a negative electrode material for lithium-ion batteries and / or sodium-ion batteries and / or potassium-ion batteries.

[0009] The objective of this invention is achieved through the following solution:

[0010] A method for preparing a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material includes the following steps:

[0011] (1) Bismuth precursors are treated by liquid reduction to obtain porous elemental bismuth;

[0012] (2) Disperse the porous elemental bismuth obtained in step (1) into a system containing a carbon matrix precursor to form a uniform and stable dispersion, freeze dry, and obtain a mixed aerogel.

[0013] (3) The mixed aerogel obtained in step (2) is calcined under a protective atmosphere to obtain a two-dimensional carbon matrix sheet embedded monodisperse bismuth nanosphere composite material.

[0014] The bismuth precursor in step (1) is at least one of bismuth oxide, bismuth sulfide, bismuth selenide, bismuth oxybromide, bismuth oxychloride, bismuth oxyiodide, bismuth oxycarbonate, and bismuth oxyselenide.

[0015] The reducing agent used in the liquid reduction method described in step (1) is one of hydrazine hydrate, sodium borohydride, or ascorbic acid.

[0016] The molar ratio of the bismuth precursor to the reducing agent in step (1) is 0.1-2.5:1.

[0017] In step (1), the liquid used in the liquid reduction method is at least one of water, ethanol, and methanol; wherein the ratio of liquid to reducing agent is 30-250 mL: 1-10 mmol.

[0018] The carbon matrix precursor in step (2) is at least one of graphene, two-dimensional transition metal carbide (MXene) and its derivatives, ammonium citrate, citric acid, chitosan, tartaric acid, gum arabic, cellulose and its derivatives.

[0019] The mass ratio of porous elemental bismuth to carbon matrix precursor in step (2) is 0.05-10:0.01-5.

[0020] In step (2), the ratio of solvent to carbon matrix precursor in the dispersion is 20-200 mL: 0.01-5 g.

[0021] In step (2), the dispersion is rapidly cooled with liquid nitrogen before freeze-drying.

[0022] The protective atmosphere in step (3) is at least one of argon and nitrogen.

[0023] The heating rate of calcination in step (3) is 1-20℃ / min; the calcination temperature is 300-1000℃; and the calcination holding time is 0.5-5h.

[0024] The above method prepares a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material.

[0025] Application of the above-mentioned two-dimensional carbon matrix sheet-encapsulated monodisperse bismuth nanoparticle composite material in ion batteries.

[0026] The ion battery includes one of lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries.

[0027] The two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material is used as a negative electrode material in an ion battery, including the following steps:

[0028] The anode material for ion batteries is obtained by mixing monodisperse bismuth nanospheres embedded in a two-dimensional carbon matrix sheet, carbon black, and polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, preparing a slurry, and then coating it onto copper foil.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) This invention provides a novel method for synthesizing nanomaterials based on the capillary force of nanopores to synthesize a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material. This method can simultaneously achieve the requirements of ultra-small size, ultra-high content, efficient carbon coating, and adjustable Bi content in bismuth / carbon composite materials. In the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material prepared by this invention, the ultrafine Bi nanospheres are completely embedded by a two-dimensional ultrathin oxygen-rich nitrogen-doped carbon sheet. This overall two-dimensional ultrathin and stable structure shortens the path of lithium, sodium, and potassium ions through the two-dimensional plane during charging and discharging, ensuring ultrafast electron / ion transport and extremely fast electrochemical reaction kinetics. The ultrasmall Bi nanospheres also help to reduce volume stress during the expansion process.

[0031] (2) The equipment required for this invention is simple, easy to operate, safe, and low in cost, and can be mass-produced.

[0032] (3) The two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material prepared by the present invention has a novel structure. The bismuth nanospheres embedded in the two-dimensional carbon matrix sheet are small and uniformly dispersed, with high reactivity. When used as a negative electrode material for lithium-ion batteries and / or sodium-ion batteries and / or potassium-ion batteries, it has the characteristics of high specific capacity, long cycle life and excellent rate performance. When applied to sodium-ion battery negative electrode, it has a specific capacity of 50 Ag. -1 It provides 397.8mAh g at an ultra-high current density. -1 Its ultra-high capacity output, at 10Ag -1 Under high current density conditions, it still maintained 467.3 mAh g⁻¹ after 1600 long cycles. -1 Excellent capacity. When applied to the anode of potassium-ion batteries, it achieves a capacity of 50 Ag. -1 It provides 275.8mAh g at a high current density. -1 High capacity output, at 10Ag -1 After 1200 long cycles under high current density conditions, it still maintained 330.8 mAh g. -1 Excellent capacity. Attached Figure Description

[0033] Figure 1 X-ray diffraction pattern (a) and transmission electron microscopy (B)-(d) of porous elemental bismuth obtained in Example 1.

[0034] Figure 2 X-ray diffraction pattern (a); Raman pattern (b); thermogravimetric curve (c) of the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material obtained in Example 1.

[0035] Figure 3 Transmission electron microscopy (TEM) images (a)-(d) of the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material obtained in Example 1; atomic force microscopy images and corresponding height curves (e)-(f); high-resolution TEM image (g); elemental distribution maps (h)-(l).

[0036] Figure 4 The particle size distribution diagram of Bi nanospheres in the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material obtained in Example 1 is shown.

[0037] Figure 5 The storage performance diagram is shown for the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material obtained in Example 1.

[0038] Figure 6 The image shows the potassium storage performance of the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material obtained in Example 1. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0040] Unless otherwise specified, all reagents used in the examples are commercially available.

[0041] Example 1

[0042] (1) Take 0.5 g of bismuth oxyiodide and ultrasonically disperse it in 50 mL of water to form a uniform dispersion. During stirring, slowly add 10 mL of 0.1 mol / L hydrazine hydrate solution to the dispersion and continue stirring for 30 min. After filtration, washing and drying, obtain elemental bismuth with a porous structure.

[0043] (2) Take 0.3 g of the porous elemental bismuth synthesized in step (1), disperse it evenly in 50 mL of water, then add 0.05 g of graphene and 0.05 g of chitosan, and stir vigorously for 1 h to form a uniform and stable dispersion. After rapid cooling with liquid nitrogen and freeze drying for 40 hours, a mixed aerogel is obtained.

[0044] (3) Place the mixed aerogel obtained in step (2) in a tube furnace, and under an argon atmosphere, heat at a rate of 1℃ / min and keep at 500℃ for 3 hours to obtain a two-dimensional carbon matrix sheet embedded monodisperse bismuth nanosphere composite material.

[0045] Example 2

[0046] (1) Take 0.2 g of bismuth oxychloride and 0.5 g of bismuth selenide oxychloride (Nanotechnology 2021,32,485602) and ultrasonically disperse them in 100 mL of ethanol to form a uniform dispersion. During stirring, slowly add 15 mL of 0.1 mol / L sodium borohydride solution to the dispersion and continue stirring for 30 min. After filtration, washing and drying, obtain elemental bismuth with a porous structure.

[0047] (2) Take 0.3 g of the porous elemental bismuth synthesized in step (1), disperse it evenly in 50 mL of water, then add 0.1 g of gum arabic and 0.1 g of chitosan, stir vigorously for 1 h to form a uniform and stable dispersion. After rapid cooling with liquid nitrogen and freeze drying for 40 h, a mixed aerogel is obtained.

[0048] (3) Place the mixed aerogel obtained in step (2) in a tube furnace, and under an argon atmosphere, heat at a rate of 5℃ / min and keep at 700℃ for 5h to obtain a two-dimensional carbon matrix sheet embedded monodisperse bismuth nanosphere composite material.

[0049] Example 3

[0050] (1) Take 0.5 g of bismuth oxychloride and ultrasonically disperse it in 200 mL of methanol to form a uniform dispersion. During stirring, slowly add 30 mL of 0.1 mol / L sodium borohydride solution to the dispersion and continue stirring for 30 min. After filtration, washing and drying, obtain elemental bismuth with a porous structure.

[0051] (2) Take 0.5 g of the porous elemental bismuth synthesized in step (1) and disperse it evenly in 100 mL of water. Then add 0.4 g of two-dimensional Ti3C2 material and 0.1 g of chitosan. Stir vigorously for 1 h to form a uniform and stable dispersion. After rapid cooling with liquid nitrogen and freeze drying for 40 hours, a mixed aerogel is obtained.

[0052] (3) Place the mixed aerogel obtained in step (2) in a tube furnace, and under an argon atmosphere, heat at a rate of 3℃ / min and keep at 900℃ for 2 hours to obtain a two-dimensional carbon matrix sheet embedded monodisperse bismuth nanosphere composite material.

[0053] Example 4

[0054] (1) Take 3.0 g of bismuth selenide and 2.0 g of bismuth oxybromide, and ultrasonically disperse them in 200 mL of water to form a uniform dispersion. During stirring, slowly add 50 mL of 0.1 mol / L ascorbic acid solution to the dispersion and continue stirring for 30 min. After filtration, washing and drying, obtain elemental bismuth with a porous structure.

[0055] (2) Take 4.0 g of porous elemental bismuth synthesized in step (1), disperse it evenly in 200 mL of water, then add 1.0 g of tartaric acid, and stir vigorously for 1 h to form a uniform and stable dispersion. After rapid cooling with liquid nitrogen and freeze drying for 40 hours, a mixed aerogel is obtained.

[0056] (3) Place the mixed aerogel obtained in step (2) in a tube furnace, and under an argon atmosphere, heat at a rate of 7℃ / min and keep at 1000℃ for 2 hours to obtain a two-dimensional carbon matrix sheet embedded monodisperse bismuth nanosphere composite material.

[0057] Test Implementation Example:

[0058] The two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite materials prepared in Examples 1-4 were mixed and ground with PVDF and carbon black at a mass ratio of 8:1:1 and then transferred to a small glass bottle. N-methylpyrrolidone (NMP) was added and the mixture was magnetically stirred for 1 hour. The material was then coated onto copper foil to form an electrode. A button cell was assembled in a glove box using lithium / sodium / potassium metal as the counter electrode and its electrochemical performance was tested.

[0059] The electrochemical performance of each embodiment is shown in Table 1.

[0060] Table 1

[0061]

[0062] Figure 1 X-ray diffraction pattern (a) and transmission electron microscopy (B)-(d) of porous elemental bismuth obtained in Example 1. It can be seen that porous elemental bismuth was successfully obtained in Example 1 after step (1), and its nanopores run through the entire interior and surface of the material.

[0063] After freeze-drying and calcination treatments in steps (1) and (2) of Example 1, a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material was obtained. Figure 2 The X-ray diffraction pattern in (a) and the Raman spectrum in (b) both confirmed the presence of the pure metallic Bi phase, and thermogravimetric analysis revealed that the Bi content in the material was as high as 93.06 wt%. Figure 2 The value of (c) is far higher than the level reported in current literature.

[0064] Furthermore, transmission electron microscopy revealed that the obtained two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material contained ultrafine Bi nanospheres with an average size of 10.23 nm. Figure 4 The surface was completely coated with a two-dimensional carbon matrix, and no bare Bi nanospheres were found. Figure 3 (a)-(d) and (g)). Atomic force microscopy revealed that the average thickness of the two-dimensional carbon matrix-embedded monodisperse bismuth nanosphere composite material was approximately 16.42 nm. Figure 3 The clear and continuous step height results in (e)-(f) in the figure also verify the dense distribution of ultrafine Bi nanospheres in two-dimensional ultrathin oxygen-rich nitrogen-doped carbon sheets. Figure 3 The elemental mappings of Bi, C, N and O in (h)-(l) show that dense Bi is uniformly distributed in the N-doped oxygen-rich carbon sheet.

[0065] This ultrathin, robust, monolithic two-dimensional structure shortens the path of lithium, sodium, and potassium ions across the two-dimensional plane during charging and discharging, ensuring ultrafast electron / ion transport. The good mechanical properties and toughness of the two-dimensional structure help buffer the dramatic expansion of Bi during electrochemical reactions, thus maintaining the structural stability of the material under high-rate, ultra-long-cycle conditions. When this material is applied to the anode of sodium-ion batteries, it can withstand 50Ag... -1 It provides 397.8mAh g at an ultra-high current density. -1 Its ultra-high capacity output, and at 10Ag -1 Under high current density conditions, it still maintained 467.3 mAh g⁻¹ after 1600 long cycles. -1 Excellent capacity, with no capacity decay during cycling ( Figure 5 When this material is applied to the negative electrode of a potassium-ion battery, it can achieve a yield of 50 Ag. -1 It provides 275.8mAh g at high current density. -1 High capacity output, and in 10Ag -1 Under high current density conditions, the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanosphere composite material of this invention exhibits excellent electrochemical reversibility, maintaining a current density of 330.8 mAh g⁻¹ after 1200 long cycles. -1 Excellent capacity ( Figure 6 ).

[0066] This invention provides a method for preparing and applying a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material. It employs a novel nanomaterial synthesis method based on the capillary force of nanopores. By changing the content of porous elemental bismuth obtained by liquid reduction and the carbon matrix precursor, the requirements of ultra-small size, ultra-high content, efficient carbon coating, and adjustable Bi content of Bi can be simultaneously achieved, thus meeting the needs of high-performance lithium-ion batteries and / or sodium-ion batteries and / or potassium-ion batteries as anode materials.

[0067] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material, characterized in that, Includes the following steps: (1) Bismuth precursors are treated by liquid reduction to obtain porous elemental bismuth; (2) Disperse the porous elemental bismuth obtained in step (1) into a system containing a carbon matrix precursor to form a uniform and stable dispersion, freeze dry, and obtain a mixed aerogel. (3) The mixed aerogel obtained in step (2) is calcined under a protective atmosphere to obtain a two-dimensional carbon matrix sheet embedded monodisperse bismuth nanosphere composite material. The bismuth precursor in step (1) is at least one of bismuth oxide, bismuth sulfide, bismuth selenide, bismuth oxybromide, bismuth oxychloride, bismuth oxyiodide, bismuth oxycarbonate, and bismuth oxyselenide. The reducing agent used in the liquid reduction method described in step (1) is one of hydrazine hydrate, sodium borohydride, and ascorbic acid; The molar ratio of the bismuth precursor to the reducing agent in step (1) is 0.1-2.5:1; The liquid used in step (1) of the liquid reduction method is at least one of water, ethanol, and methanol; wherein the ratio of liquid to reducing agent is 30-250 mL: 1-10 mmol. The carbon matrix precursor in step (2) is at least one of graphene, MXene and its derivatives, ammonium citrate, citric acid, chitosan, tartaric acid, gum arabic, cellulose and its derivatives; The heating rate of calcination in step (3) is 1-20℃ / min; the calcination temperature is 300-1000℃; and the calcination holding time is 0.5-5h.

2. The method for preparing the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material according to claim 1, characterized in that: The mass ratio of porous elemental bismuth to carbon matrix precursor in step (2) is 0.05-10:0.01-5; In step (2), the ratio of solvent to carbon matrix precursor in the dispersion is 20-200 mL: 0.01-5 g.

3. The method for preparing the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material according to claim 1, characterized in that: The protective atmosphere in step (3) is at least one of argon and nitrogen.

4. The two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material prepared by the method of any one of claims 1-3.

5. The application of the two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material of claim 4 in ion batteries.

6. The application according to claim 5, characterized in that: The ion battery includes one of lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries.

7. The application according to claim 5 or 6, characterized in that: The two-dimensional carbon matrix sheet-embedded monodisperse bismuth nanoparticle composite material is used as an anode material in ion batteries.

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