Alpha-MoC1-x/Si@C microsphere and preparation method and application thereof

Abstract

The invention discloses an alpha-MoC1-x / Si@C microsphere and a preparation method and application thereof. Carbon with dopamine as a carbon source forms a micron-level sphere as a framework, ammonium molybdate in a precursor provides molybdenum, a large number of molybdenum carbide particles are formed in situ on a carbon substrate and serve as a large carbon / molybdenum carbide conductive carrier, nano silicon dioxide wrapped by the carbon matrix is reduced into nano silicon particles which are firmly wrapped by the carbon skeleton, so that a spherical structure that the nano silicon particles are distributed in the carbon / molybdenum carbide main body is formed. According to the invention, the initial morphology of the material is well retained by using a mild magnesiothermic method, and the reduced Si is coated by a carbon layer, so that the volume expansion of the material in the lithium intercalation and deintercalation process can be improved, and the cycle life is prolonged.

Description

Technical field[0001]The present invention relates to the preparation of a composite, in particular, to aluminum chloride (AlCl)3) Molten salt-assisted low-temperature magnesia thermal reduction method prepared spherical carbide / silicon (α-MOC)1-x / Si @ C) Composites and their applications in the negative electrode of lithium ion batteries.Background technique[0002]With the rapid development of technology, people's demand for high-energy density energy storage devices is growing. Lithium-ion batteries have developed as one of the most widely used energy storage devices in recent decades due to significant advantages of high energy density, high open circuit voltage, charge and discharge rate, environmentally friendly, etc., especially today's portable electronic equipment and new Energy cars are increasingly important in human society, and lithium-ion batteries are still an important research direction. Although the basic research and application of lithium-ion batteries have exce...

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Problems solved by technology

But the carrier material Ti 3 C 2 Via precursor Ti 3 AlC 2 It is obtained by long-time etching with concentrated hydrofluoric acid, which is risky and harmful to the environment, and is not suitable for practical applications; and the uniform distribution of commercial silicon particles cannot be guaranteed by ultrasonic dispersion; while the document "Employing MXene as a matrix for In loading amorphous Sigenerated upon lithiation towards enhanced lithium-ion storage (Journal of Energy Chemistry 38 (2019) 50-54), the author used a milder etching method: lithium fluoride mixed with hydrochloric acid solution to etch Ti 3 AlC 2 , but this method has a long treatment process, and the subsequent washing process of impurities is complicated, and the experimental period is long, and the author also uses commercial silicon ultrasonic dispersion method to compound the material, so it is also not suitable for practical application; and in the literature "MXene / Si@SiO x @C Layer-by-Layer Superstructure with AutoadjustableFunction for Superior Stable Lithium Storage (ACS Nano 2019, 13, 2167−2175)", the author used in-situ synthesis to synthesize two-dimensional Ti 3 C 2 The surface is hydrolyzed to form silica, and then reduced to silicon by magnesia thermal reduction method. This method can synthesize silicon particles that are uniform and firmly bonded to the matrix. However, in practical applications, the control of silicon content is complicated and high-temperature magnesia thermal Reduction may damage the microstructure of the product and increase energy consumption

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