Silicon-carbon negative electrode material with porous surface and tiny hollow spheres and preparation method of silicon-carbon negative electrode material

Abstract

The invention discloses a surface porous micro hollow sphere silicon-carbon negative electrode material and a preparation method thereof, the surface porous micro hollow sphere silicon-carbon negative electrode material comprises a silicon monoxide hollow sphere, the sphere surface is of a porous structure, and the silicon monoxide surface forming the hollow sphere is provided with a carbon coating layer. The preparation method mainly comprises the following steps: step 1, adding silicon monoxide powder into polyvinylidene chloride emulsion, and stirring and dispersing to obtain slurry; 2, taking polystyrene microspheres as a core material, coating the polystyrene microspheres with the slurry prepared in the step 1, granulating, and drying to obtain spherical particles; and step 3, performing high-temperature carbonization on the spherical particles, so that the polystyrene microspheres and the polyvinylidene chloride are heated and decomposed to form a carbon coating layer. According to the method, polystyrene microspheres and polyvinylidene chloride are decomposed through high-temperature carbonization to form a hollow structure and a porous structure, a carbon coating layer is formed, the problem of pollution caused by a traditional process is avoided, and the process only comprises three steps of stirring, granulation and carbonization, and is simple and easy to implement.

Description

technical field [0001] The invention relates to the field of battery materials, in particular to a surface porous micro-hollow spherical silicon carbon negative electrode material and a preparation method thereof. Background technique [0002] With the rapid development of the needs of the times, the energy density of lithium-ion batteries is increasing at a rate of 7-10% per year. According to the "Technical Roadmap for Energy-Saving and New Energy Vehicles", the energy density target of pure electric vehicle power batteries is 350Wh / kg. Silicon can be alloyed with lithium at room temperature, and the theoretical specific capacity is as high as 3572mAh / g, which is much higher than the theoretical specific capacity of commercial graphite. Silicon is rich in reserves, low cost and environmentally friendly. Therefore, silicon anode is the most potential next-generation lithium One of the anode materials for ion batteries. [0003] However, silicon suffers from severe volume ...

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Problems solved by technology

This method does not provide a preparation method for silicon-aluminum-carbon ternary materials, and the first Coulombic efficiency of this material is low, and the cycle performance is still not ideal

Chinese patent CN102157731A discloses a silicon-carbon composite negative electrode material for lithium-ion batteries and its preparation method. The method first uses magnesia thermal reduction of mesoporous silica to prepare a porous silicon matrix, and then carbon coating to obtain a silicon-carbon composite negative electrode material. The cost of mesoporous silica and magnesium powder used in this method is high, which is unfavorable for industrialized production

Chinese patent CN1442916A discloses a silicon-aluminum-aluminum / carbon composite material for negative electrodes of lithium-ion batteries and its preparation method. The method adopts a two-step sintering method, firstly preparing silicon-aluminum alloys by mechanical ball milling-high-temperature calcination of silicon powder and aluminum powder, Then the organic polymer is cracked, graphite powder is added to it, and then the prepared silicon aluminum alloy is added to form a slurry, which is finally prepared by heating and reacting in a sealed system. The addition of aluminum in the material reduces the capacity of the composite material. Resulting in lower capacity, and due to poor cycle stability, cannot meet the requirements of commercial high-energy power supplies

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