Poly-3, 4-ethylenedioxythiophene multi-loaded cobaltosic oxide polyhedral negative electrode material and preparation method and application thereof

Abstract

The invention discloses a poly-3, 4-ethylenedioxythiophene / porous cobaltosic oxide polyhedral negative electrode material as well as a preparation method and application thereof, and belongs to the field of lithium ion battery materials. The method comprises the following steps: (1) adding a 2-methylimidazole methanol solution into a cobalt nitrate hexahydrate methanol solution for reaction, and standing to obtain a cobalt metal organic metal framework; (2) calcining the cobalt organic metal framework obtained in the step (1) at high temperature to obtain a porous cobaltosic oxide polyhedron; (3) dissolving 3, 4-ethylenedioxythiophene in water, then adding the porous cobaltosic oxide polyhedron and sodium thiosulfate, and stirring for reaction; the poly (3, 4-ethylenedioxythiophene) multi-loaded porous cobaltosic oxide compound obtained by the invention improves the conductivity of the material and solves the problem of volume expansion in the charge-discharge process, and has a good application prospect in the field of lithium ion batteries.

Description

Technical Field

[0001] The invention belongs to the field of lithium ion battery materials, and specifically relates to a poly 3,4-ethylenedioxythiophene / porous cobalt tetroxide polyhedron negative electrode material and a preparation method and application thereof. Background Art

[0002] As energy and environmental issues become increasingly severe, human beings have an increasingly urgent need for high-capacity lithium-ion batteries. The main components of lithium-ion batteries are positive electrode materials, negative electrode materials, separators and electrolytes. Among them, the selection of suitable negative electrode materials plays a vital role in the energy density of lithium-ion batteries. At present, the lithium-ion battery negative electrode materials commonly used in the market are mainly graphite negative electrode materials, which have a theoretical capacity of 372mAh / g and cannot meet the needs of the next generation of high-energy lithium-ion batteries. Transition metal oxides have attracted the attention of researchers due to their wide variety of options. Transition metal oxides have the following advantages: (1) They have a high theoretical specific capacity; the theoretical specific capacity of transition metal oxides is much higher than that of commercial graphite negative electrode materials, such as MnO 2 1232 mAh / g, Fe 2 O 3 1007mAh / g, Fe 3 O 4 924mAh / g, Co 3 O 4 890mAh / g, CuO 673mAh / g, etc.; (2) It has many advantages such as abundant natural reserves, low price, less environmental pollution, etc. However, transition metal oxides have many disadvantages as negative electrode materials for lithium-ion batteries: (1) Transition metal oxides themselves have poor conductivity, which is not conducive to charge transfer during charging and discharging; (2) Transition metal oxides are prone to significant volume changes during charging and discharging, resulting in pulverization of electrode materials, reduced connections between each other, and increased system resistance; or they fall off from the surface of the current collector, resulting in loss of active materials.

[0003] To solve the above problems, people have adopted many methods, among which combining transition metal oxides with highly conductive materials is a common method. In addition, layered hollow nanostructures are an effective way to alleviate volume changes during charging and discharging. The porous structure can not only reduce the diffusion path of lithium ions, but also has a large specific surface area to fully contact the electrolyte. Therefore, the preparation of a poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron negative electrode material can effectively improve the lithium storage performance of the battery. Summary of the invention

[0004] In view of the shortcomings and deficiencies of the above prior art, the primary purpose of the present invention is to provide a method for preparing a poly (3,4-ethylenedioxythiophene) / porous cobalt trioxide polyhedron negative electrode material.

[0005] Another object of the present invention is to provide a poly (3,4-ethylenedioxythiophene) / porous cobalt trioxide polyhedron negative electrode material prepared by the above method.

[0006] The object of the present invention is to provide the application of the poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron in the fields of lithium ion batteries and the like.

[0007] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron negative electrode material comprises the following steps: (1) 2-methylimidazole and cobalt nitrate hexahydrate are added to methanol for ultrasonic treatment respectively, and then the 2-methylimidazole methanol solution is added to the cobalt nitrate hexahydrate methanol solution, and the mixture is allowed to stand, and then the solution after the reaction is filtered to obtain a cobalt organic metal framework; (2) calcining the cobalt organic metal framework obtained in step (1) at high temperature to obtain porous cobalt trioxide polyhedrons; (3) Add 3,4-ethylenedioxythiophene to deionized water, then add concentrated hydrochloric acid and stir to react. (4) Add the porous cobalt trioxide polyhedron and ammonium persulfate obtained in step (2) to the mixed solution obtained in step (3), and stir to react. (5) Add 3,4-ethylenedioxythiophene to the mixed solution of step (4), continue stirring the reaction, and finally centrifuge to obtain the poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron negative electrode material.

[0008] In step (1), the content of 2-methylimidazole in methanol is preferably 0.5-0.8 wt %. The purity of methanol is preferably 99.99%.

[0009] Preferably, 2-methylimidazole can be dispersed in methanol by ultrasound. The ultrasound temperature is 25-33° C. and the ultrasound time is 5-10 min.

[0010] In step (1), the content of cobalt nitrate hexahydrate in methanol is 0.5-0.8 wt %. The purity of methanol is preferably 99.99%.

[0011] Preferably, the hexahydrated cobalt nitrate can be dispersed in methanol by ultrasound. The ultrasound temperature is 25-33°C and the ultrasound time is 5-10 minutes. The 2-methylimidazole dispersion is added to the hexahydrated cobalt nitrate methanol solution and then allowed to stand for 2-6 hours.

[0012] The size of the cobalt organic metal framework obtained in step (1) is preferably 1-2 μm, more preferably 1.5 μm.

[0013] In step (2), the calcination atmosphere is an air atmosphere.

[0014] In step (2), the calcination temperature is preferably 450-550° C., and the calcination time is preferably 2-4 hours.

[0015] In step (3), the volume fraction of 3,4-ethylenedioxythiophene in deionized water is 0.3-0.5%. The purity of 3,4-ethylenedioxythiophene is 99%. The volume fraction of concentrated hydrochloric acid in deionized water is 0.35-0.50%. The concentration of concentrated hydrochloric acid is 36-38%.

[0016] Preferably, the stirring time is 30-40 min.

[0017] In step (4), the amount of the porous cobalt trioxide polyhedron added is 0.15-0.3 g. The amount of the ammonium persulfate added is 0.2-0.3 g. The concentration of the ammonium persulfate is 99%.

[0018] Preferably, the stirring reaction time is 4.5-7h.

[0019] In step (5), the volume fraction of 3,4-ethylenedioxythiophene in deionized water is 0.3-0.5%. The purity of 3,4-ethylenedioxythiophene is 99%.

[0020] Preferably, the stirring reaction time is 4.5-7h.

[0021] The present invention also provides a poly 3,4-ethylenedioxythiophene multi-loaded cobalt tetroxide negative electrode material obtained by the above-mentioned preparation method, and the poly 3,4-ethylenedioxythiophene with high conductivity is multi-loaded on the surface of cobalt tetroxide through the polymerization of 3,4-ethylenedioxythiophene. The material of the present invention is coated with a complete and dense poly 3,4-ethylenedioxythiophene layer on the surface of cobalt tetroxide. This structure can effectively improve the conductivity of the electrode material, and at the same time provide a soft protective layer, improve the stress of the material, reduce the impact of the volume expansion of cobalt tetroxide during the charging and discharging process, and thereby improve the cycle capacity and cycle performance of lithium ion batteries. Therefore, it has good application prospects in the fields of lithium ion batteries.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention forms a dense soft coating layer on the surface of porous cobalt tetroxide through the polymerization of 3,4-ethylenedioxythiophene, thereby improving the electrochemical performance of lithium-ion batteries.

[0023] (2) The present invention forms a complete and dense coating layer on the surface of porous cobalt tetroxide by adding 3,4-ethylenedioxythiophene twice. The porous nano-cobalt tetroxide has a large specific surface area, which can provide a larger contact area between the electrode and the electrolyte, increase the active sites of the reaction, and provide a more effective lithium ion transmission channel. At the same time, the poly 3,4-ethylenedioxythiophene coating layer can improve the conductivity of the electrode and reduce the formation of the solid electrolyte membrane. The stable and complete poly 3,4-ethylenedioxythiophene coating layer can alleviate the problem caused by the volume expansion of porous cobalt tetroxide during the cycle process, and the structure can effectively improve the stress resistance of the material, thereby improving the cycle capacity and cycle stability of the lithium-ion battery.

[0024] (3) The present invention adopts a solution polymerization method to prepare the negative electrode material of poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron, which has a simple process and low equipment requirements and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a SEM image of cobalt oxide (A) poly-3,4-ethylenedioxythiophene / porous cobalt oxide polyhedron (B) prepared in Example 1 of the present invention.

[0026] Figure 2 It is a SEM picture of poly 3,4-ethylenedioxythiophene / porous cobalt trioxide polyhedron-1 prepared in the comparative example of the present invention.

[0027] Figure 3 This is a TEM image of the poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron prepared in Example 1 of the present invention.

[0028] Figure 4 This is an XRD diagram of the porous cobalt oxide and poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron prepared in Example 1 of the present invention.

[0029] Figure 5 This is a graph showing the electrochemical performance test results of the poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron prepared in Example 1 of the present invention as a negative electrode material for a lithium-ion battery.

[0030] Figure 6 The electrochemical performance test results of poly 3,4-ethylenedioxythiophene / porous cobalt tetroxide polyhedron prepared in Example 1 of the invention as a negative electrode material for lithium-ion batteries under high rate current DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, all raw materials and reagents in the present invention are commercially available conventional raw materials and reagents.

[0032] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0033] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1) and allowed to react for 5 h. After the reaction, the mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0034] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0035] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 35 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0036] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0037] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h, then centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0038] Comparative Example: (1) Add 0.980 g of 2-methylimidazole into 150 mL of methanol and disperse by ultrasonication for 5 min at a temperature of 30 °C to obtain a 2-methylimidazole mixed solution.

[0039] (2) Add 0.525 g of cobalt nitrate hexahydrate to 90 mL of methanol, perform ultrasonic dispersion for 8 min, then mix with the mixed solution of step (1), let stand for reaction for 5 h, centrifuge after the reaction, rinse with deionized water 3 times, and dry at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0040] (3) The cobalt organic metal framework obtained in step (2) is calcined in an air atmosphere at a high temperature of 450° C. for 3 h to obtain porous cobalt trioxide polyhedrons.

[0041] (4) Add 200 μL of 3,4-ethylenedioxythiophene and 160 μL of HCl into 35 mL of deionized water and stir for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0042] (5) 0.2 g of the cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), stirred for reaction for 5 h, and then centrifuged. The mixture was rinsed with deionized water for 3 times and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt trioxide polyhedron-1.

[0043] In order to test the performance of the negative electrode materials prepared in this embodiment and the comparative example, the poly 3,4-ethylenedioxythiophene / porous cobalt oxide polyhedron, poly 3,4-ethylenedioxythiophene / porous cobalt oxide polyhedron-1 and porous cobalt oxide obtained in this embodiment were used as negative electrode materials to assemble lithium ion batteries. The mass ratio of negative electrode material: conductive acetylene black: PVDF thickener was 7:2:1, mixed into a slurry, coated on copper foil and dried in a vacuum drying oven for 12 hours to form a negative electrode sheet, which was combined with a lithium sheet to form a lithium ion half-cell, and the electrolyte was 1 mol / L LiPF 6 / (EC+DME), the diaphragm is Celgard2400 membrane.

[0044] The SEM images of the porous cobalt oxide polyhedron and poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron prepared in this example are shown in FIG. Figure 1 As shown. Figure 1 A shows that the method of the present invention obtains porous cobalt oxide, which is about 1 μm in size and has a porous surface structure. Figure 1 B shows that the surface of the poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron obtained by the method of the present invention is covered by a dense poly (3,4-ethylenedioxythiophene) film, and the porous particles cannot be observed.

[0045] The SEM image of poly (3,4-ethylenedioxythiophene) / porous cobalt tetraoxide polyhedron-1 prepared in the comparative example is shown in FIG. Figure 2 As shown. Figure 2 It can be seen that the surface of the poly (3,4-ethylenedioxythiophene) / porous cobalt tetraoxide polyhedron-1 obtained in the comparative example is covered with PEODT, but Figure 2 B shows that some small porous cobalt oxide particles are exposed, indicating that their surface is not completely covered by poly (3,4-ethylenedioxythiophene).

[0046] The TEM images of the porous cobalt oxide and poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron negative electrode materials prepared in this example are shown in Figure 2. Figure 3 As shown in A and B. It can be seen that the interior of the porous cobalt oxide is a core-shell layered structure. Figure 3 As shown in B, the poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron is covered by a dense poly (3,4-ethylenedioxythiophene) film, and the polyhedron structure disappears.

[0047] The XRD patterns of the porous cobalt oxide, poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron-1 and poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron prepared in this example are shown in FIG. Figure 4 As shown, it can be seen that the characteristic peaks of poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron-1 and poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron are consistent with those of porous cobalt tetroxide, which indicates that the coating layer of poly (3,4-ethylenedioxythiophene) is an amorphous structure.

[0048] The cycle performance test results of the lithium ion battery assembled in this embodiment are as follows: Figure 5 As shown. Figure 4 It can be seen that at low current, the rate performance of porous cobalt oxide is better than that of poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron-1 and poly (3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron. -1 ), the performance of poly(3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron-1 and poly(3,4-ethylenedioxythiophene) / porous cobalt oxide polyhedron is better than that of porous cobalt oxide. -1 The capacity of poly(3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron was maintained at 527 mAh g -1 The capacity of poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron-1 is 440 mAh g -1 , while the capacity of porous cobalt tetroxide is only 360 mAh g -1 After rate cycling, the capacity of poly(3,4-ethylenedioxythiophene) / porous cobalt tetraoxide polyhedron reached 932 mAh g after 100 cycles at 0.3C. -1 , which is higher than the theoretical specific capacity of cobalt tetroxide (840 mAh g -1 ), after 200 cycles, the capacity of poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron remains at 586 mAh g -1 In comparison, the capacity of poly(3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron-1 was 325 mAh g after 200 cycles at 0.3C. -1 , while the capacity of porous cobalt tetroxide after 200 cycles is only 4 mAh g -1 ,It can be seen that poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron exhibits better electrochemical performance.

[0049] Figure 6 Poly(3,4-ethylenedioxythiophene) / porous cobalt tetraoxide polyhedron is a promising candidate for high current 1 A g -1From the cycle diagram, it can be seen that after 200 cycles, the capacity reaches 711 mA g -1 , the coulombic efficiency remains stable, which shows that the dense and complete poly (3,4-ethylenedioxythiophene) coating layer can improve the conductivity of the electrode and enhance the transfer rate of lithium ions. At the same time, the soft coating layer can alleviate the impact of volume expansion.

[0050] 0.990 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0051] 0.535 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1), allowed to react for 5 h, rinsed with deionized water 3 times, dried at 70° C. for 12 h, and centrifuged after the reaction to obtain a cobalt organic metal framework.

[0052] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0053] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 35 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0054] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0055] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0056] 0.980 g of 2-methylimidazole was added to 140 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0057] 0.525 g of cobalt nitrate hexahydrate was added to 80 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1), allowed to react for 5 h, rinsed with deionized water 3 times, dried at 70° C. for 12 h, and centrifuged after the reaction to obtain a cobalt organic metal framework.

[0058] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 500° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0059] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 35 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0060] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0061] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0062] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0063] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1) and allowed to react for 4 h. After the reaction, the mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0064] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 2 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0065] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 35 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0066] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0067] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0068] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0069] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1), allowed to react for 5 h, rinsed with deionized water 3 times, dried at 70° C. for 12 h, and centrifuged after the reaction to obtain a cobalt organic metal framework.

[0070] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0071] 210 μL of 3,4-ethylenedioxythiophene and 165 μL of 3,4-ethylenedioxythiophene were added to 35 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0072] 0.15 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0073] 210 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0074] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0075] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1), allowed to react for 5 h, rinsed with deionized water 3 times, dried at 70° C. for 12 h, and centrifuged after the reaction to obtain a cobalt organic metal framework.

[0076] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0077] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 35 mL of deionized water and stirred for 30 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0078] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 4 h.

[0079] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 4 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0080] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0081] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1) and allowed to react for 5 h. After the reaction, the mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0082] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0083] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 40 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0084] 0.25 g of cobalt trioxide obtained in step (3) and 0.30 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0085] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0086] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at an ultrasonic temperature of 28°C to obtain a 2-methylimidazole mixed solution.

[0087] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at an ultrasonic temperature of 28° C. Then, the mixture was mixed with the mixed solution of step (1) and allowed to react for 5 h. After the reaction, the mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0088] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 550° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0089] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 40 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0090] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0091] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0092] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0093] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1) and allowed to react for 4 h. After the reaction, the mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0094] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 2 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0095] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 40 mL of deionized water and stirred for 30 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0096] 0.2 g of cobalt trioxide obtained in step (3) and 0.2 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 5 h.

[0097] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 5 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0098] 0.980 g of 2-methylimidazole was added to 150 mL of methanol and ultrasonically dispersed for 5 min at a temperature of 30°C to obtain a 2-methylimidazole mixed solution.

[0099] 0.525 g of cobalt nitrate hexahydrate was added to 90 mL of methanol and ultrasonically dispersed for 8 min at a temperature of 30° C. Then, the mixture was mixed with the mixed solution of step (1) and allowed to react for 5 h. After the reaction, the mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain a cobalt organic metal framework.

[0100] The cobalt organic metal framework obtained in step (2) is calcined at a high temperature of 450° C. for 3 h in an air atmosphere to obtain porous cobalt trioxide polyhedrons.

[0101] 200 μL of 3,4-ethylenedioxythiophene and 160 μL of 3,4-ethylenedioxythiophene were added to 40 mL of deionized water and stirred for 35 min to obtain a 3,4-ethylenedioxythiophene mixed solution.

[0102] 0.25 g of cobalt trioxide obtained in step (3) and 0.25 g of ammonium persulfate were added to the mixed solution obtained in step (4), and the mixture was stirred for reaction for 4 h.

[0103] 200 μL of 3,4-ethylenedioxythiophene was added to the mixed solution obtained in step (5), and the mixture was stirred and reacted for 4 h. The mixture was centrifuged, rinsed with deionized water for 3 times, and dried at 70° C. for 12 h to obtain poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron.

[0104] The above embodiments are the optimal implementation modes explored by the present invention, but the implementation modes of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement methods and shall be included in the protection scope of the present invention.

Claims

1. A poly (3,4-ethylenedioxythiophene) / porous cobalt trioxide polyhedron negative electrode material and its preparation method and application, characterized by the following steps: (1) 2-methylimidazole and cobalt nitrate hexahydrate are added to methanol for ultrasonic treatment respectively, and then the 2-methylimidazole methanol solution is added to the cobalt nitrate hexahydrate methanol solution, and the mixture is allowed to stand, and then the solution after the reaction is filtered to obtain a cobalt organic metal framework; (2) calcining the cobalt organic metal framework obtained in step (1) at high temperature to obtain porous cobalt trioxide polyhedrons; (3) Add 3,4-ethylenedioxythiophene to deionized water, then add concentrated hydrochloric acid and stir to react. (4) Add the porous cobalt trioxide polyhedron and ammonium persulfate obtained in step (2) to the mixed solution obtained in step (3), and stir to react. (5) Add 3,4-ethylenedioxythiophene to the mixed solution of step (4), continue stirring the reaction, and finally centrifuge to obtain the poly (3,4-ethylenedioxythiophene) / porous cobalt tetroxide polyhedron negative electrode material.

2. The preparation method according to claim 1, characterized in that: In step (1), the content of 2-methylimidazole in methanol is 0.5-0.8 wt %.

3. The preparation method according to claim 1, characterized in that: In step (1), the content of cobalt nitrate hexahydrate in methanol is 0.5-0.8wt%; the standing time is 4-6h, and the reaction temperature is 30-35°C.

4. The preparation method according to claim 1, characterized in that: In step (2), the calcination temperature is 450-550°C and the reaction time is 2-4h.

5. The preparation method according to claim 1, characterized in that: In step (3), the volume fraction of 3,4-ethylenedioxythiophene in deionized water is 0.3-0.5%.

6. The preparation method according to claim 1, characterized in that: In step (3), the concentration of concentrated hydrochloric acid is 36-38 wt %, its volume fraction in deionized water is 0.35-0.50%, and the reaction time is 0.5-1 h.

7. The preparation method according to claim 1, characterized in that: In step (4), the amount of porous cobalt oxide added is 0.15-0.3 g.

8. The preparation method according to claim 1, characterized in that: In step (4), the amount of ammonium persulfate added is 0.2-0.3 g, and the reaction time is 4.5-7 h.

9. The preparation method according to claim 1, characterized in that: In step (5), the volume fraction of 3,4-ethylenedioxythiophene in deionized water is 0.3-0.5%, and the reaction time is 4.5-7h. 10 . The poly (3,4-ethylenedioxythiophene) / porous cobalt trioxide polyhedron negative electrode material according to claim 8 is used in a lithium ion battery.

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