Nano-silicon and silicon/carbon composite material based on cut silicon waste, and preparation method and application thereof

Abstract

The invention discloses a nano silicon and silicon / carbon composite material based on cut silicon waste and a preparation method and application thereof. The preparation method of the nano silicon comprises the following steps: mixing the cut silicon waste and metal magnesium powder, performing tabletting, performing wrapping with foamed nickel, and binding the mixture on a metal molybdenum rod current collector by using a fine molybdenum wire to serve as an anode; connecting the metal molybdenum rod with a stainless steel current collector to serve as a cathode; taking magnesium salt as molten salt; and performing soaking and alloying for 0.5-3 hours in the molten magnesium salt, applying a voltage of 1-2 V to the soaked and alloyed anode and cathode, carrying out constant-current electrolysis for 2-12 hours, taking out the anode and cathode, performing cooling, cleaning, pickling and drying to obtain the nano silicon; mixing carbon precursors and nano-silicon, and performing ultrasonic dispersion and hydrothermal-in-situ polymerization and pyrolysis carbonization to obtain a silicon / carbon composite material. The nano-silicon and silicon / carbon composite material prepared by the method shows good discharge specific capacity, rate capability and cycling stability, and the method has the advantages of rich raw materials, low cost, simple operation process and the like.

Description

technical field [0001] The invention relates to a nano-silicon and silicon / carbon composite material based on cutting silicon waste, a preparation method and an application thereof, and belongs to the technical field of preparation of nano-silicon and silicon / carbon nano-composite materials. Background technique [0002] Lithium-ion batteries have been widely used in portable electronic devices such as mobile phones, digital cameras and notebook computers, and are expected to become the energy source of electric vehicles and hybrid vehicles that have emerged in recent years, and have important commercial value. LiCoO is currently the cathode material for commercial lithium-ion batteries 2 , LiMn 2 o 4 、LiFePO 4 And ternary materials, etc.; the negative electrode material is graphite and various carbon materials with graphite as the precursor. Although carbon materials have good reversible charge-discharge performance, their theoretical capacity is low (372mAh / g), and the...

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Problems solved by technology

For example, CN1891668A discloses a silicon / carbon composite material with a core-shell structure prepared from ultrafine commercial silicon particles. Although the nanostructure of the silicon material and the introduction of the carbon shell layer have improved the cycle performance, the prepared by this method The content of silicon in the material is low, resulting in a low mass specific capacity of the silicon-carbon composite electrode material; CN102208636B discloses a porous silicon / carbon composite material prepared from diatomite and its application, and the micron-sized natural diatomite The porous silicon obtained by the metal reduction method is used, and the silicon / carbon composite is prepared from porous silicon, but the porous silicon particles and the silicon / carbon composite material described in this method still have a micron size, and the natural diatomite is removed There are many impurity steps, the process is complicated and energy-consuming

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