A preparation method of silicon-carbon negative electrode material for lithium ion battery

Abstract

The invention discloses a preparation method of a silicon-carbon negative electrode material of a lithium ion battery, comprising the following steps: adding a proper amount of nano-silicon powder, adispersant, zinc nitrate hexahydrate, terephthalic acid and CNTs to a sufficient amount of N, N- A mixed solution is prepared from dimethylformamide, and then the mixed solution is uniformly dispersed; A suitable amount of triethylamine reagent is slowly and uniformly adde into that mixture prepared in the first step, aft full reaction, the precipitate is washed, filtered and dried to obtain CNTs / MOF- 5, coat that nano Si precursor; The precursor was put into a tubular furnace protected by inert gas and carbonized at high temperature to obtain silicon-carbon composites. Silicon-carbon anode materials for lithium ion batteries were prepared by mixing the prepared silicon-carbon composite and artificial graphite homogeneously. CNTs is adde into that preparation process of the silicon-carbonnegative electrode material of the lithium ion battery, and the CNTs can be use as a conductive network structure, the electronic conductivity of the silicon-carbon negative electrode is greatly improved, and the first effect and the multiplicity of the charge-discharge cycle of the silicon-carbon negative electrode are improved.

Description

technical field [0001] The invention belongs to the field of lithium-ion batteries, and relates to a preparation method of a silicon-carbon negative electrode material of a lithium-ion battery. Background technique [0002] At the end of the 20th century, with the development of portable consumer electronics (mobile phones, video cameras, portable computers), the field of batteries has received a new impact, and batteries with high energy density are urgently needed to meet market demand. However, lead-acid batteries were not suitable for these applications, and attention was turned to nickel-cadmium batteries, but were eventually surpassed by lithium-ion batteries (LIB) in the early 1990s. As part of our everyday life, LIBs have been continuously improved over the past 25 years and have received a great deal of research attention. [0003] Today LIBs also play a vital role in many fields from electric vehicles to energy storage for alternative energy sources (solar, wind, ...

AI Technical Summary

Problems solved by technology

As we all know, the negative electrode of traditional lithium-ion batteries mainly uses graphite, and its theoretical specific capacity is only 372mAh / g, which is difficult to meet the needs of today's social development. However, silicon (Si) has a high specific capacity, and lithium ions and Si are alloyed to form Si 22 Li 5 , the theoretical specific capacity can be as high as 4200mAh / g, and has a low lithium intercalation potential, which is a very potential lithium ion negative electrode material

However, Si also has its own disadvantages. Si is a semiconductor material with low intrinsic conductivity (10 -5 ~10 -3 S / cm), the lithium ion diffusion coefficient is low (10 -14 ~10 -13 cm 2 / s), and during the charge-discharge cycle, the insertion and extraction of lithium ions will cause the Si negative electrode to expand and shrink by more than 300%, and the mechanical stress generated will gradually pulverize the Si material, and the newly exposed Si surface New SEI films are continuously formed, causing irreversible loss of lithium ions, collapse of the structure, and eventually falling off from the current collector, resulting in rapid degradation of cycle performance

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