Mesoporous hollow carbon nanospheres in-situ grown tin hydroxide cobalt nanocube composite materials and their preparation and application

Abstract

The present invention discloses a composite material of mesoporous hollow carbon nanospheres in-situ growing cobalt stannate hydroxide nanocubes, a preparation method thereof, and an application thereof in preparing an anode of a lithium-ion battery. In the composite material of mesoporous hollow carbon nanospheres in-situ growing cobalt stannate hydroxide nanocubes, CoSn(OH)6 nanocubes are in-situ grown in the inner cavity of the mesoporous hollow carbon nanospheres, mesoporous channels for making the shell permeable are distributed on the shell of the mesoporous hollow carbon nanospheres, CoSn(OH)6 nanocubes also exist in the mesoporous channels, and the mesoporous channels can prevent the CoSn(OH)6 nanocubes thereon and in the inner cavity of the mesoporous hollow carbon nanospheres from leaking. The present invention fills cobalt nitrate into the mesoporous hollow carbon nanospheres by a method of high-speed centrifugal injection of an aqueous solution, calcines to obtain CoO, sucks molten Na2SnO3·3H2O into the mesoporous hollow carbon nanospheres by capillary action, and obtains the composite material through a melting reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion battery negative electrode, and in particular to a method for in-situ growth of cobalt tin hydroxide (CoSn(OH)) on mesoporous hollow carbon nanospheres. 6 )Nanocube composite materials and preparation methods and applications thereof. Background Art

[0002] CoSn(OH) 6 It has a wide range of applications in electrochemical capacitors, electrocatalysts, photocatalysts, etc. CoSn(OH) 6 It has a highly active Faradaic reaction, high energy density, and high power density, and is a very promising supercapacitor electrode material. CoSn(OH) 6 As the negative electrode material of lithium-ion batteries, it also has a high reversible capacity because the hydroxyl group in the metal hydroxide can reversibly react with Li ions to form LiOH. The formed LiOH can further reversibly react with Li ions to form LiH and Li 2 O. These two reactions lead to CoSn(OH) 6 The theoretical specific capacity is very high.

[0003] Limit CoSn(OH) 6 The main problem in the application of lithium-ion batteries is its low conductivity and large volume change, resulting in low rate performance and poor cycle stability. Unfortunately, there is only one paper reporting on CoSn(OH) 6 and graphene composite (CoSn(OH) 6 hybridized with anionic and cationic graphenes as a new high-capacity anode for lithium ion batteries,Materials and Design 2017,118,294–303), in addition, CoSn(OH) 6 There is almost no research on its application in lithium-ion batteries. Summary of the invention

[0004] In view of the above technical problems and the shortcomings in the art, the present invention provides a mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material (also referred to as CoSn(OH) 6 @Mesoporous hollow carbon nanospheres), with good structure and cycle stability, and excellent lithium storage performance.

[0005] A mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material, wherein CoSn(OH) 6 Nanocubes and mesoporous hollow carbon nanospheres have mesoporous channels distributed on their shells to make the shells transparent, and CoSn(OH) 6 Nanocubes, the mesoporous channels can block the CoSn(OH) on them and in the inner cavity of the mesoporous hollow carbon nanospheres 6 Nanocubes leaked.

[0006] Preferably, the outer diameter of the mesoporous hollow carbon nanospheres is 100-1000 nm, and the shell thickness is 10-100 nm.

[0007] Preferably, the size of the mesoporous channel is less than 10 nm.

[0008] Preferably, the CoSn(OH) in the inner cavity of the mesoporous hollow carbon nanospheres 6 The side length of the nanocube is 10-100nm, and the CoSn(OH) 6 The size of the nanocubes is less than 10 nm.

[0009] Preferably, in the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material, CoSn(OH) 6 The quality percentage is 20%-80%.

[0010] Preferably, the mesoporous hollow carbon nanospheres are amorphous carbon materials formed by decomposing RF resin (phenolic resin).

[0011] The present invention also provides a method for preparing the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material, comprising the steps of:

[0012] (1) soaking the mesoporous hollow carbon nanospheres in a cobalt nitrate aqueous solution, allowing the solution to stand to obtain a black precipitate, removing the supernatant, and centrifuging the remaining mixture at 10,000-20,000 rpm for multiple times, then drying the precipitate, and heating the dried product to 440-460° C. in an inert gas atmosphere for 1.5-2.5 h to obtain CoO@mesoporous hollow carbon nanospheres;

[0013] (2) CoO@mesoporous hollow carbon nanospheres and Na 2 SnO 3 ·3H 2 O is mixed by ball milling, heated to 155-165° C. under vacuum conditions and kept warm for 1.5-2.5 hours, and then cooled, washed and dried to obtain the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material.

[0014] The present invention uses a method of high-speed centrifugal injection of aqueous solution to inject Co(NO 3 ) 2 Filled with mesoporous hollow carbon nanospheres, calcined to obtain cobalt oxide, and the molten Na 2 SnO 3 ·3H 2 O is absorbed into the mesoporous hollow carbon nanospheres, and finally Na 2 SnO 3 ·3H 2 In-situ transformation of O and CoO into CoSn(OH) 6 Nanocubes, CoSn(OH) 6 @Mesoporous hollow carbon nanospheres. The present invention can effectively improve CoSn(OH) 6 The conductivity can effectively lock the powdered CoSn(OH) 6 , strengthen the structure and cycle stability of the composite material. The synthesis process of the invention is simple and mild, and the obtained composite material has a unique structure.

[0015] It should be noted that if the CoO@mesoporous hollow carbon nanospheres in step (1) are exposed to air for too long, a small amount of CoO may be oxidized to Co 3 O 4 (These Co 3 O 4 It cannot be observed by transmission electron microscopy but can be characterized by X-ray diffraction) and cannot be compared with Na 2 SnO 3 ·3H 2 O further reacts to form CoSn(OH) 6 Nanocubes. In the mesoporous hollow carbon nanospheres in-situ grown tin hydroxide cobalt nanocube composite material of the present invention, Co 3 O 4 It can be considered as an impurity that is difficult to avoid and remove, but it does not affect CoSn(OH) 6 @The electrochemical properties of mesoporous hollow carbon nanospheres themselves are negatively affected.

[0016] The present invention can adopt the template method to synthesize mesoporous hollow carbon nanospheres.

[0017] Preferably, in step (1), the method for preparing mesoporous hollow carbon nanospheres comprises the steps of:

[0018] (a) Add tetrapropoxysilane to an ethanol aqueous solution of ammonia, mix well, add resorcinol and formaldehyde, and after sufficient reaction, wash and dry the resulting precipitate to obtain SiO 2 @RF resin / SiO 2 ;

[0019] (b) SiO 2 @RF resin / SiO 2 Carbonize at 500-800℃ for 1-3h in an inert gas atmosphere to obtain SiO 2 @Carbon / SiO 2 ;

[0020] (c) Etching SiO with hydrofluoric acid 2 @Carbon / SiO 2 Removal of SiO 2 , washing and drying to obtain the mesoporous hollow carbon nanospheres.

[0021] A preparation method of the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material comprises the following steps:

[0022] 1) Slowly add 3.0 mL of ammonia water (25-28 wt%) to a mixed solution of 70 mL of ethanol and 10 mL of deionized water. After stirring for 15 min in a water bath at 25°C, add 3.46 mL of tetrapropoxysilane and continue stirring for 5-45 min. Then add 0.1-1 g of resorcinol and 0.1-1 mL of formaldehyde aqueous solution (35-40 wt%) respectively, stir for 24 h, and obtain a light yellow precipitate, which is washed with deionized water and dried at 60°C to obtain SiO 2 @RF resin / SiO 2 Put it into a tube furnace and carbonize it in an argon atmosphere at a carbonization temperature of 500-800°C for 1-3h to obtain SiO 2 @Carbon / SiO 2 . Hydrofluoric acid solution (25.0 wt%) was used to etch away SiO 2 , washed with deionized water, and dried at 60 °C to obtain mesoporous hollow carbon nanospheres.

[0023] 2) 2-20g Co(NO 3 ) 2 6H 2 O was dissolved in 100mL of deionized water, and then 0.025g of mesoporous hollow carbon nanospheres was added and soaked for 24h to obtain a black precipitate. The supernatant was extracted and the remaining mixture was centrifuged 3 times at a speed of 10,000-20,000 rpm for 6min each time. After centrifugation, the supernatant was extracted and the remaining precipitate was dried at 60°C. The dried product was placed in a tubular furnace and heated to 450°C in an argon atmosphere for 2h to obtain CoO@ mesoporous hollow carbon nanospheres. 0.02g of CoO@ mesoporous hollow carbon nanospheres and 0.02-0.20g of Na 2 SnO 3 ·3H 2O was placed in a small micro-vibration ball mill and mixed thoroughly for 3 times, each time for 20 seconds. The mixed sample was placed in an oven, evacuated, and heated to 160°C for 2 hours. After cooling, the product was washed with deionized water 3 times, centrifuged, and dried at 60°C. CoSn(OH) was obtained. 6 @Mesoporous hollow carbon nanospheres.

[0024] The mesoporous hollow carbon nanospheres of the present invention can significantly improve the specific capacity and cycle stability of cobalt tin hydroxide and are an excellent negative electrode material for lithium ion batteries.

[0025] The present invention also provides the use of the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material in preparing a negative electrode of a lithium ion battery.

[0026] Compared with the prior art, the present invention has the following main advantages:

[0027] 1. The present invention uses a method of high-speed centrifugal injection of aqueous solution to inject Co(NO 3 ) 2 Fill the mesoporous hollow carbon nanospheres and calcine them into high melting point CoO; then 2 SnO 3 ·3H 2 O and CoO@mesoporous hollow carbon nanospheres were fully mixed and heated to Na 2 SnO 3 ·3H 2 O above the melting point, so that the molten Na 2 SnO 3 ·3H 2 O can be absorbed into the mesoporous hollow carbon nanospheres through capillary action and react chemically with CoO to generate CoSn(OH) 6 In this reaction, Na 2 SnO 3 The crystal water is the key. Without crystal water, the reaction will not proceed. If the entire material is put into the aqueous solution, the reaction will be too violent and CoSn(OH) 6 Mainly grows outside the mesoporous hollow carbon nanospheres. 2 SnO 3 The crystal water reacts in the molten state. The reaction is mild and controllable and can only be carried out inside the mesoporous hollow carbon nanospheres. 2 SnO 3 ·3H 2 O is removed by water washing. This method can ensure that CoSn(OH) 6 In situ growth inside mesoporous hollow carbon nanospheres.

[0028] 2. Mesoporous hollow carbon nanospheres can improve the internal CoSn(OH)6 The mesoporous channels on the shell facilitate the penetration of electrolyte, and the large internal space can store electrolyte, promoting the 6 Full contact with the electrolyte. The large internal space allows CoSn(OH) 6 Free expansion and contraction minimizes internal stress. The semi-enclosed space can effectively lock CoSn(OH) 6 Even if it is powdered, it cannot fall off from the carbon nanospheres, ensuring the integrity of the composite material.

[0029] 3. Due to CoO and Na 2 SnO 3 ·3H 2 O is injected into the mesoporous hollow carbon nanospheres before reacting, and the filling amount is limited, resulting in CoSn(OH) 6 The formation reaction is very mild, and the grown cubes are small in size, so they have high electrochemical activity and excellent lithium storage performance. The pores of the mesoporous shell are also inlaid with ultrafine CoSn(OH) 6 , which is an important supplement to the performance of the central large cube. The synergistic cooperation of the two brings excellent lithium storage performance. Mesoporous hollow carbon nanospheres for CoSn(OH) 6 The growth has a unique confinement effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a transmission electron microscope (TEM) photograph of the mesoporous hollow carbon nanospheres prepared in Example 1;

[0031] Figure 2 TEM image of CoO@mesoporous hollow carbon nanospheres prepared in Example 1;

[0032] Figure 3 CoSn(OH) prepared in Example 1 6 @Scanning electron microscope (SEM) image of mesoporous hollow carbon nanospheres;

[0033] Figure 4 CoSn(OH) prepared in Example 1 6 @TEM image of mesoporous hollow carbon nanospheres;

[0034] Figure 5 CoSn(OH) prepared in Example 1 6 @XRD pattern of mesoporous hollow carbon nanospheres;

[0035] Figure 6 CoSn(OH) prepared in Example 1 6 @High-resolution transmission electron microscopy (HRTEM) image of mesoporous hollow carbon nanospheres;

[0036] Figure 7 CoSn(OH) prepared in Example 1 6 @Mesoporous hollow carbon nanospheres and mesoporous hollow carbon nanospheres, pure CoSn(OH) 6 At a current density of 1 A g -1 The cycle performance diagram below. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0038] Example 1

[0039] (1) 3.0 mL of ammonia water (25-28 wt%) was slowly added to a mixed solution of 70 mL of ethanol and 10 mL of deionized water. After stirring for 15 min in a water bath at 25°C, 3.46 mL of tetrapropoxysilane was added and the stirring was continued for 15 min. Then 0.4 g of resorcinol and 0.56 mL of formaldehyde aqueous solution (37 wt%) were added respectively and stirred for 24 h to obtain a light yellow precipitate, which was washed with deionized water and dried at 60°C to obtain SiO 2 @RF resin / SiO 2 It was placed in a tube furnace and carbonized under an argon atmosphere at a temperature of 600°C for 2 hours to obtain SiO 2 @Carbon / SiO 2 . Hydrofluoric acid solution (25.0 wt%) was used to etch away SiO 2 , washed with deionized water, and dried at 60 °C to obtain mesoporous hollow carbon nanospheres.

[0040] (2) 10g Co(NO 3 ) 2 6H 2 O was dissolved in 100mL of deionized water, and then 0.025g of mesoporous hollow carbon nanospheres was added and soaked for 24h to obtain a black precipitate. The supernatant was extracted and the remaining mixture was centrifuged 3 times at a speed of 15,000 rpm for 6min each time. After centrifugation, the supernatant was extracted and the remaining precipitate was dried at 60℃. The dried product was placed in a tubular furnace and heated to 450℃ in an argon atmosphere for 2h to obtain CoO@ mesoporous hollow carbon nanospheres. 0.02g of CoO@ mesoporous hollow carbon nanospheres and 0.1g of Na 2 SnO 3 ·3H 2O was placed in a small micro-vibration ball mill and mixed thoroughly for 3 times, each time for 20 seconds. The mixed sample was placed in an oven, evacuated, and heated to 160°C for 2 hours. After cooling, the product was washed with deionized water 3 times, centrifuged, and dried at 60°C. CoSn(OH) was obtained. 6 @Mesoporous hollow carbon nanospheres.

[0041] Figure 1 This is a TEM photo of mesoporous hollow carbon nanospheres. The outer diameter of the carbon spheres is about 200-250nm, the shell thickness is 30-50nm, and the diameter of the mesoporous channels on the shell is less than 5nm. Figure 2 This is a TEM photo of CoO@mesoporous hollow carbon nanospheres. It can be seen that there are a large number of CoO particles inside the mesoporous hollow carbon nanospheres, which are evenly distributed in the inner cavity and have a size of about 10nm. Figure 3 CoSn(OH) 6 @The SEM photo of the mesoporous hollow carbon nanospheres still shows a smooth nanosphere shape, which appears to be more textured than CoO@mesoporous hollow carbon nanospheres, indicating that a material with higher hardness is generated inside, resulting in a decrease in the light transmittance of the nanospheres. No impurities are observed outside the carbon spheres, which is very clean, indicating that the reaction is mainly concentrated inside the mesoporous hollow carbon spheres. Figure 4 The TEM photo shows that the uniformly sized small particles inside the carbon sphere are transformed into larger cubes. There are 1-2 cubes inside each mesoporous hollow carbon sphere, and the cube size is about 50nm. There are also some CoSn(OH) in the mesoporous channels of the spherical shell. 6 Small cubic particles make the shell darker, and the particle size is about 2nm. In addition to CoSn(OH) 6 There are also a lot of empty spaces outside the cube, which provide buffer space and electrolyte storage space.

[0042] Figure 5 CoSn(OH) 6 @XRD spectrum of mesoporous hollow carbon nanospheres. The diffraction peaks at 2θ of 22.84°, 32.52°, 40.11°, 46.66°, 52.56°, 58.03°, 68.12°, 72.88°, 77.53°, 82.104° and 86.62° are similar to those of CoSn(OH) 6 (JCPDS No.74-0365) The crystal planes (200), (220), (222), (400), (420), (422), (440), (442), (620), (622) and (444) are consistent, indicating that CoSn(OH) 6 In addition, three diffraction peaks appeared at 2θ of 36.84°, 44.80°, and 65.23°, which were similar to Co 3 O 4(JCPDS No.74-2120) corresponds to the card, which indicates that the material also contains Co 3 O 4 This is because when CoO@ mesoporous hollow carbon nanospheres are stored in the air, cobalt oxide is oxidized, which makes it unable to react with Na 2 SnO 3 ·3H 2 O reaction, and no Co was observed by HRTEM. 3 O 4 Crystalline particles, only CoSn(OH) 6 ,like Figure 6 A wider hump appears between 20° and 30°, which is attributed to the mesoporous hollow carbon nanospheres of amorphous carbon in the composite material.

[0043] Thermogravimetric analysis under air shows that the CoSn(OH) 6 and Co 3 O 4 The quality accounts for 55% and 14% respectively.

[0044] The CoSn(OH) 6 @Mesoporous hollow carbon nanosphere composite material for making lithium-ion battery negative electrode: Weigh CoSn(OH) with a mass ratio of 80:10:10 respectively 6 @Mesoporous hollow carbon nanosphere composite material, acetylene black conductive agent, PVDF binder, dissolve PVDF in an appropriate amount of N-methylpyrrolidone, stir until completely dissolved, then add the evenly ground active material and acetylene black to the above solution, continue stirring to ensure that the slurry is evenly mixed. Then evenly coat the slurry on a disc copper foil (diameter 12mm), dry it in a vacuum oven at 100℃, and finally flatten it on a tablet press with a pressure of 10MPa to obtain an electrode sheet.

[0045] The prepared electrode sheet, lithium sheet and diaphragm were assembled into a CR2025 button-type lithium-ion battery in a glove box filled with high-purity argon. The electrolyte was 1 mol / L LiPF 6 EC / DMC electrolyte is used to test the charge and discharge performance and cycle performance of lithium-ion batteries using the Xinwei battery testing system.

[0046] Figure 7 CoSn(OH) 6 @Mesoporous hollow carbon nanospheres and mesoporous hollow carbon nanospheres, pure CoSn(OH) 6 At a current density of 1A -1 Cycling performance diagram of CoSn(OH) 6 @Mesoporous hollow carbon nanospheres showed 1193 mAh g in the first cycle -1The high capacity of the discharge capacity remained stable in the subsequent cycles, with an average discharge capacity of 1064 mAh g -1 The capacity of the 400th cycle is 1023 mAh g -1 The discharge capacity of mesoporous hollow carbon nanospheres increased from 955 mAh g to -1 Down to 285mAh g -1 , and then stabilized, with the specific capacity remaining at 318 mAh g -1 The discharge capacity of the 400th cycle is 339 mAh g -1 . Pure CoSn(OH) 6 The first cycle discharge capacity reached 1557 mAh g -1 However, the specific capacity decays rapidly, and after 25 cycles the specific capacity decreases to 250 mAh g -1 , and then the specific capacity slowly decayed and stabilized at ~159 mAh g -1 The discharge capacity of the 400th cycle is 133 mAh g -1 . You can see CoSn(OH) 6 @The cycling performance of mesoporous hollow carbon nanospheres is relatively good compared with pure CoSn(OH) 6 There is a significant improvement, the discharge capacity of the 400th cycle is pure CoSn(OH) 6 7.7 times of that of CoSn(OH) 6 The lithium storage capacity and cycle stability of CoSn(OH) 6 @The discharge capacity of mesoporous hollow carbon nanospheres is 3 times that of mesoporous hollow carbon nanospheres, indicating that CoSn(OH) 6 @The high capacity of mesoporous hollow carbon nanospheres mainly comes from CoSn(OH) 6 , rather than carbon balls.

[0047] Example 2

[0048] (1) 3.0 mL of ammonia water (25-28 wt%) was slowly added to a mixed solution of 70 mL of ethanol and 10 mL of deionized water. After stirring for 15 min in a water bath at 25°C, 3.46 mL of tetrapropoxysilane was added and stirring continued for 20 min. Then 0.44 g of resorcinol and 0.62 mL of formaldehyde aqueous solution (37 wt%) were added respectively and stirred for 24 h to obtain a light yellow precipitate, which was washed with deionized water and dried at 60°C to obtain SiO 2 @RF resin / SiO 2 It was placed in a tube furnace and carbonized under an argon atmosphere at a temperature of 600°C for 2 hours to obtain SiO 2 @Carbon / SiO 2. Hydrofluoric acid solution (25.0 wt%) was used to etch away SiO 2 , washed with deionized water, and dried at 60 °C to obtain mesoporous hollow carbon nanospheres.

[0049] The subsequent steps are the same as those in Example 1.

[0050] Product CoSn(OH) 6 @The structure of the mesoporous hollow carbon nanosphere composite material is similar to that of Example 1, the main difference being that the outer diameter of the mesoporous hollow carbon nanosphere is increased to 250-300 nm. CoSn(OH) 6 The morphology remains unchanged, and the mass proportion in the composite material is 49wt%, Co 3 O 4 The mass proportion is 12wt%.

[0051] Example 3

[0052] (1) 3.0 mL of ammonia water (25-28 wt%) was slowly added to a mixed solution of 70 mL of ethanol and 10 mL of deionized water. After stirring for 15 min in a water bath at 25°C, 3.46 mL of tetrapropoxysilane was added and the stirring was continued for 15 min. Then 0.4 g of resorcinol and 0.56 mL of formaldehyde aqueous solution (37 wt%) were added respectively and stirred for 24 h to obtain a light yellow precipitate, which was washed with deionized water and dried at 60°C to obtain SiO 2 @RF resin / SiO 2 It was placed in a tube furnace and carbonized under an argon atmosphere at a temperature of 600°C for 2 hours to obtain SiO 2 @Carbon / SiO 2 . Hydrofluoric acid solution (25.0 wt%) was used to etch away SiO 2 , washed with deionized water, and dried at 60 °C to obtain mesoporous hollow carbon nanospheres.

[0053] (2) 8g Co(NO 3 ) 2 6H 2 O was dissolved in 100mL of deionized water, and then 0.025g of mesoporous hollow carbon nanospheres was added and soaked for 24h to obtain a black precipitate. The supernatant was extracted and the remaining mixture was centrifuged 3 times at a speed of 15,000 rpm for 6min each time. After centrifugation, the supernatant was extracted and the remaining precipitate was dried at 60°C. The dried product was placed in a tubular furnace and heated to 450°C in an argon atmosphere for 2h to obtain CoO@ mesoporous hollow carbon nanospheres. 0.02g of CoO@ mesoporous hollow carbon nanospheres and 0.08g of Na 2 SnO 3 ·3H 2O was placed in a small micro-vibration ball mill and mixed thoroughly for 3 times, each time for 20 seconds. The mixed sample was placed in an oven, evacuated, and heated to 160°C for 2 hours. After cooling, the product was washed with deionized water 3 times, centrifuged, and dried at 60°C. The product CoSn(OH) was obtained. 6 @Mesoporous hollow carbon nanospheres.

[0054] Product CoSn(OH) 6 @The structure of the mesoporous hollow carbon nanosphere composite material is similar to that of Example 1, the main difference is that CoSn(OH) 6 and Co 3 O 4 The quality accounts for 44% and 11% respectively.

[0055] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a composite material of in-situ growth of mesoporous hollow carbon nanospheres and cobalt hydroxide nanocubes, It is characterized in that In situ growth of CoSn(OH) in the inner cavity of mesoporous hollow carbon nanospheres 6 Nanocubes and mesoporous hollow carbon nanospheres have mesoporous channels distributed on their shells to make the shells transparent, and CoSn(OH) 6 Nanocubes, the mesoporous channels can block the CoSn(OH) on them and in the inner cavity of the mesoporous hollow carbon nanospheres 6 Nanocubes leaked out; The method for preparing the composite material of in-situ growth of mesoporous hollow carbon nanospheres and cobalt hydroxide nanocubes comprises the following steps: (1) Immersing the mesoporous hollow carbon nanospheres in a cobalt nitrate aqueous solution, allowing the mixture to stand to obtain a black precipitate, removing the supernatant, and centrifuging the remaining mixture at 10,000-20,000 rpm for multiple times, then drying the precipitate. The dried product is heated to 440-460° C. in an inert gas atmosphere for 1.5-2.5 h to obtain CoO@mesoporous hollow carbon nanospheres; (2) CoO@mesoporous hollow carbon nanospheres and Na 2 SnO 3 ·3H 2 O is mixed by ball milling, heated to 155-165° C. under vacuum conditions and kept warm for 1.5-2.5 h, and then cooled, washed and dried to obtain the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material.

2. The method for preparing the composite material of mesoporous hollow carbon nanospheres in-situ grown tin cobalt hydroxide nanocubes according to claim 1, It is characterized in that The outer diameter of the mesoporous hollow carbon nanospheres is 100-1000 nm, and the shell thickness is 10-100 nm; The size of the mesoporous channel is less than 10 nm; CoSn(OH) in the cavity of mesoporous hollow carbon nanospheres 6 The side length of the nanocube is 10-100 nm, and the CoSn(OH) 6 The size of the nanocubes is less than 10 nm.

3. The method for preparing the composite material of in-situ growth of mesoporous hollow carbon nanospheres and cobalt hydroxide nanocubes according to claim 1, It is characterized in that In the mesoporous hollow carbon nanosphere in-situ grown tin hydroxide cobalt nanocube composite material, CoSn(OH) 6 The quality percentage is 20%-80%.

4. The method for preparing the composite material of in-situ growth of mesoporous hollow carbon nanospheres and cobalt tin hydroxide nanocubes according to claim 1, It is characterized in that The mesoporous hollow carbon nanospheres are amorphous carbon materials formed by decomposing RF resin.

5. The method for preparing the composite material of in-situ growth of mesoporous hollow carbon nanospheres and cobalt hydroxide nanocubes according to claim 1, It is characterized in that In step (1), the method for preparing mesoporous hollow carbon nanospheres comprises the steps of: (a) Add tetrapropoxysilane to an ethanol solution of ammonia water, mix well, add resorcinol and formaldehyde, and after sufficient reaction, wash and dry the resulting precipitate to obtain SiO 2 @RF resin / SiO 2 ; (b) SiO 2 @RF resin / SiO 2 Carbonization at 500-800 °C for 1-3 h in a rare gas atmosphere yields SiO 2 @Carbon / SiO 2 ; (c) Etching SiO with hydrofluoric acid 2 @Carbon / SiO 2 Removal of SiO 2 , washing and drying to obtain the mesoporous hollow carbon nanospheres.

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