- Preparation of Co3O4/TiO2 secondary heterostructures
(1) Preparation of TiO2 nanofibers
A certain amount of PVP was weighed into 5 mL of ethanol and 1 mL of acetic acid, and stirred magnetically for about 6 hours at room temperature to obtain a viscous, transparent and uniform solution with a polymer concentration of 8%. Then, 1.5 mL of n-butyl titanate was rapidly added dropwise to the above solution, and the solution was rapidly stirred for about 2 h to obtain a transparent light yellow liquid.
The above transparent and uniform spinning solution is loaded into a syringe with a stainless steel flattened needle, the syringe with spinning solution is installed on the electrospinning device, and electrospinning parameters are set, and the specific parameters are: add to the spinneret The electrostatic voltage between it and the receiving plate is 15kV, the vertical distance between the spinneret and the receiving plate is 18cm, the propelling speed of the syringe pump is set to 1.0mL/h, and a flat plate receiving device wrapped in an aluminum box is used. The composite nanofiber membrane spun above was placed in a tube furnace, and was heated from room temperature to 500 °C for 12 h at a heating rate of 5 °C/min in an air atmosphere, and then cooled to room temperature naturally. samples for characterization and performance testing.
(2) Preparation of Co3O4/TiO2 secondary heterostructures
0.2429g Co(NO3)2•6H2O and 0.25g urea were dissolved in 25mL deionized water and stirred until dissolved. Then, the above solution was placed in a reaction vessel containing 20 mg of TiO2 film, and reacted at 120 °C for 6 h. After cooling to room temperature, the film was removed and washed with water and ethanol. The collected films were dried in a vacuum drying box at 50°C for 12h, placed in a tube furnace, and calcined for 12h from room temperature to 500°C at a heating rate of 5°C/min in an air atmosphere, and then naturally cooled to room temperature. For comparison experiments, no TiO2 film was added to the reaction kettle, and other reaction steps were the same to prepare Co3O4 nanomaterials.
This method can be extended to prepare other metal oxide/TiO2 secondary heterostructures. Other conditions are the same, 0.243g FeC13 is used as the precursor, and the reaction is carried out at 90 °C for 6 h in the reaction kettle. Fe2O3/TiO2 secondary heterostructure can be obtained without calcination. The other conditions are the same. Dissolve 0.25g FeC13•6H2O, 0.25g polyethylene glycol, and 0.9g sodium acetate in 25mL ethylene glycol, and react in the reaction kettle at 200 ℃ for 16h. Fe3O4/TiO2 secondary isoform can be obtained without calcination. qualitative structure. Dissolve 0.2557g CuCl2•2H2O and 0.3g urea in 30mL water, react at 180℃ for 12h in a reaction kettle, and calcinate at 500℃ for 2h in air to obtain CuO/TiO2 secondary heterostructure.
- Characterization of Co3O4/TiO2 Secondary Heterostructure
The morphology of the samples was analyzed by FEI Tacnai G2 transmission electron microscope and HITACHIS4800 field emission scanning electron microscope. The structure of the material was tested by the German Bruker D8 X-ray diffractometer and CuKα ray (λ=0.15406nm). The thermal analysis curve of the sample was tested in the air atmosphere by using the STA449F3 thermogravimetric and differential thermal (TG/DSC) synchronous analyzer produced by the German NETZSCH company. The heating rate was 5 °C/min, and the cooling was a natural cooling process. The ESCALABMKI II photoelectron spectrometer of Thermo Company in the United States, the ray source is AlKa ray, with C1s (284.6eV) as the calibration standard, the test vacuum degree is less than 10-8Pa, the working voltage is 12kV, the current is 20mA, and the step size is 0.1eV. The Raman spectrum was measured using an instrument from Renishaw Company, an Ar ion laser with an emission wavelength of 532 nm, and the powder sample was directly placed on a glass slide for testing.
- Electrochemical performance test of Co3O4/TiO2 secondary heterostructure
The active material, binder (polyvinylidene fluoride, PVDF) and conductive agent (acetylene black) were mixed in a mass ratio of 7:2:1, and after adding N-methylpyrrolidone (NMP), they were ground for a period of time, so that the mixture was in the grinding process. Mix well in the bowl. It was then coated on copper foil and dried at 80°C for 8h. Electrode pieces with a diameter of 12 cm were formed using a punching machine and weighed. A 2025 button cell was assembled in a glove box, using a lithium sheet as the counter electrode and reference electrode, using a Celgard 2400 separator, using LiPF6 (1mol/L)/EC:DMC (1:1, mass ratio) as the Electrolyte. Cyclic voltammetry and constant current charge-discharge tests were performed on the battery. The cyclic voltammetry test was tested by the VMP3 electrochemical workstation of Biologic Company, and the constant current charge and discharge test was tested by the charge and discharge instrument of Wuhan Blue Electric Company.
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