Preparation method and application of three-dimensional honeycomb-shaped nano Si

Abstract

The invention belongs to the technical field of preparation of nano Si and relates to a preparation method and application of three-dimensional honeycomb-shaped nano Si. The preparation method comprises the following steps: adding granular carbon with the d50 of 0.2 to 5mu m into an electrolyte metal ion solution before the granular carbon is cladded; uniformly dispersing by ultrasonic waves or anemulsifying machine, so as to adsorb metal ions on surfaces of micron-grade Si grains; after cladding the surfaces of the micron-grade Si grains with a carbon material, carrying out rapid perforationon the inner part of the Si by utilizing a metal ion attachment point when an HF solution or a mixed solution of HF and HO- is used for etching the inner part of the Si, so as to cut an inner structure of the micron Si and form a perfect nano space structure of a three-dimensional space network honeycomb-shaped structure. Therefore, volume expansion of lithium ions of a lithium ion battery in a disembedding process in the Si is facilitated, and the disadvantages in the prior art that the inner part is powdered by the volume expansion, an electrode structure is damaged and the cycling life ofthe lithium ion battery is rapidly attenuated are avoided; the three-dimensional honeycomb-shaped nano Si is used for a negative electrode material of the lithium ion battery and generated cycling performance is extremely excellent and attenuation is scarcely reduced.

Description

technical field [0001] The invention belongs to the technical field of nano-Si preparation, in particular to a preparation method and application of three-dimensional honeycomb nano-Si. Background technique [0002] Electrochemical energy storage, mainly represented by lithium-ion batteries, has been greatly favored because of its environmental friendliness, long cycle life, small self-discharge, and higher energy density than other types of batteries. The Ministry of Industry and Information Technology and the Ministry of Science and Technology proposed that by 2020, the capacity density of battery cells should reach 350wh / kg, the system should reach the goal of 260wh / kg, and the manufacturing cost should be reduced to less than 1 yuan per watt to achieve this goal. , the country’s annual subsidies for new energy vehicles can be completely cancelled, and companies can improve their own technology and participate in market competition to survive the fittest. However, the cur...

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Problems solved by technology

[0002] Electrochemical energy storage, mainly represented by lithium-ion batteries, has been greatly favored because of its environmental friendliness, long cycle life, small self-discharge, and higher energy density than other types of batteries. The Ministry of Industry and Information Technology and the Ministry of Science and Technology proposed that by 2020, the capacity density of battery cells should reach 350wh / kg, the system should reach the goal of 260wh / kg, and the manufacturing cost should be reduced to less than 1 yuan per watt to achieve this goal. , the country’s annual subsidies for new energy vehicles can be completely cancelled, and the improvement of the company’s own technology can participate in market competition and the survival of the fittest. However, the current traditional graphite anode materials or hard and soft carbon anode materials can no longer meet the requirements of this goal. , there is an urgent need to develop low-cost, high-capacity next-generation battery materials. At present, high-nickel ternary + silicon-carbon composite negative electrodes will become the mainstream material system for power batteries. The theoretical capacity of Si materials is about 4200mAh / g, which is higher than traditional graphite negative electrodes. The carbon negative electrode material is nearly 10 times higher than the theoretical capacity of silicon monoxide, but the volume expansion of Si (silicon) is as high as 300% during the process of highly deintercalating lithium, which will cause problems of pulverization and peeling That is, destroying the structure of the battery motor will also lead to the continuous formation of SEI film on the surface of Si particles, resulting in continuous consumption of electrolyte, which seriously affects the cycle performance of the battery. Unfavorable problems, nano-Si, hollow Si, Si-graphite composite and synthetic SiO materials have come out one after another. Judging from the current market structure, SiO is also a research direction for high-capacity negative electrode materials, and has been used in a relatively small amount of mixed applications in actual production, but SiO The theoretical capacity is also about 1700mAh / g, but SiO is still facing a big problem. The first efficiency is too low, which can reach the highest 60%. Separately used for battery negative pole

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