Method for preparing silicon-carbon compound from silicon-containing biomass as raw material as well as prepared silicon-carbon compound and application thereof

Abstract

The invention provides a method for preparing a silicon-carbon compound from silicon-containing biomass as a raw material. The method comprises the following steps: performing acid boiling treatment on the silicon-containing biomass so as to remove inorganic salt ion impurities, washing, drying, grinding into powder, carbonizing in inert atmosphere so as to obtain a composite product of silicon dioxide and carbon, uniformly mixing the carbonized product, magnesium powder and molten salts, and putting into a tubular furnace to react in inert atmosphere, thereby obtaining a porous silicon-carbon composite material that porous silicon nanoparticles are uniformly distributed in carbon. The method is simple and feasible in process and rich and cheap in raw material, the reaction temperature is controlled as heat is absorbed when the added molten salts are molten, the structure that silicon dioxide is naturally embedded into organisms in original silicon-containing biomass is well maintained in the obtained silicon-carbon compound, and moreover, the obtained silicon nanoparticles are uniform in particle size distribution and can be applied to the field of lithium ion battery cathode materials.

Description

technical field [0001] The invention belongs to the technical field of comprehensive biological waste resources, and in particular relates to a method for preparing a silicon-carbon composite by using silicon-containing biomass as a raw material, the prepared silicon-carbon composite and its application. Background technique [0002] As a green and clean energy, lithium-ion batteries have the advantages of high working voltage, high energy density, and low self-discharge rate. They are widely used in various portable electronic devices. Speed ​​increases. At present, the anode materials of commercial lithium-ion batteries are mainly graphite-like carbon (C) materials, but the theoretical lithium storage capacity of carbon materials is only 372mAh / g, which cannot meet people's demand for high energy density materials. The theoretical lithium storage capacity of silicon (Si) is as high as 4200mAh / g, more than 10 times the theoretical capacity of graphite, and the voltage plat...

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Problems solved by technology

[0003] However, there are two fatal shortcomings of silicon as a negative electrode material: one is that during the intercalation / deintercalation process of lithium, there is a serious volume change (400%), which leads to rapid capacity decay and poor cycle performance; Semiconductor, which itself conducts electricity very poorly

[0004] The preparation of silicon-carbon composite electrode materials in the current literature and patents is achieved by a multi-step method. First, silicon or carbon is synthesized, and then another component is loaded by physical and chemical methods. The commonly used method is pyrolysis. , ball milling method, vapor deposition method and polymerization-pyrolysis method, etc. The silicon-carbon composite materials obtained by these methods have poor uniformity, high cost, serious pollution, and large-scale production cannot be realized.

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