A lithium-replenishing porous silicon monoxide negative electrode material used in a lithium ion battery and a preparation method thereof

Abstract

The invention relates to a lithium-supplementing porous silicon monoxide negative electrode material for lithium ion batteries and a preparation method thereof, and belongs to the technical field of preparation of lithium ion battery materials. The lithium-supplementing porous silicon monoxide negative electrode material is characterized in that the lithium-supplementing porous silicon monoxide negative electrode material is of a core-shell structure, porous silicon monoxide serves as an inner core, a nitrogen-doped carbon material serves as a shell, and the thickness of the shell is 50-500 nm. The lithium-supplementing porous silicon monoxide negative electrode material has the advantages that a carbon layer is uniformly deposited on the surface of the porous silicon monoxide, so that theporous silicon monoxide is prevented from directly contacting with the electrolyte, the occurrence probability of side reactions is reduced, and the electric conductivity is improved; meanwhile, by adopting the nitrogen-doped carbon material, the electric conductivity of a cladding layer can be further improved, and accordingly, the rate performance in lithium-supplementing porous silicon-carboncompounding is improved.

Description

technical field [0001] The invention relates to a lithium-supplementing porous silicon monoxide negative electrode material used in a lithium-ion battery and a preparation method thereof, belonging to the technical field of preparation of lithium-ion battery materials. Background technique [0002] As the market's requirements for the energy density of lithium-ion batteries increase, the anode materials used in lithium-ion batteries are required to have high specific capacity and cycle performance. At present, the commonly used anodes for lithium-ion batteries are mainly graphite materials, and their theoretical capacity is only 372mAh / g. It is far from meeting the demand for negative electrodes of lithium-ion batteries with a high specific energy density of 300WH / g. Silicon material (nano-silicon, silicon-oxygen compound) is an ideal lithium battery negative electrode material with abundant reserves and wide sources. However, silicon also has some disadvantages as a negativ...

AI Technical Summary

Problems solved by technology

Silicon material (nano-silicon, silicon-oxygen compound) is an ideal lithium battery negative electrode material with abundant reserves and wide sources. However, silicon also has some disadvantages as a negative electrode material: high expansion rate, poor conductivity and its ability to absorb liquid Deviation, resulting in its cycle performance and rate performance deviation affecting its use

One of the most commonly used methods to solve the above problems is to make silicon porous to form porous silicon or porous silicon-metal alloys, which can not only alleviate the volume expansion in the process of lithium storage, but also the metal dispersed in porous silicon can enhance its conductivity and improve Its rate performance, and at the same time pre-lithiation of silicon-based materials improves the first-time efficiency of its materials, and finally improves the cycle performance and energy density of its silicon-carbon composite materials; for example, the patent (application number: 201711008723.6) discloses a lithium battery negative electrode The preparation method of the material nanoporous silicon, which mainly prepares the porous nano-silicon material by vacuum heat treatment to improve the specific energy and cycle performance of the material, but the low efficiency and poor conductivity of the nano-silicon affect its rate performance and its material The first efficiency play; the patent (application number: 201310007838.9) discloses a preparation method of silicon monoxide / carbon composite negative electrode material for lithium ion batteries. The preparation method is to use ethyl orthosilicate as the silicon source and use sol-gel The porous silicon monoxide with xerogel or airgel structure is prepared by the method and the atmospheric pressure drying process, and the porous silicon monoxide is ball milled, and the nano-silicon monoxide / carbon composite negative electrode material is prepared by carbon coating and heat treatment. , the prepared porous pore size distribution is not uniform, the preparation process is complicated and the initial efficiency is low, which affects its cycle performance

It can be seen from the above that the existing preparation of porous silicon monoxide or the preparation process is complicated, the cost is high, the consistency is poor, and the first-time efficiency is low, which makes it difficult to greatly improve its performance, and these methods are often not suitable for large-scale production , hindering the industrialization process of porous silicon anode materials

In summary, the existing methods for preparing porous silicon still have defects such as complex process, high cost, low efficiency, and difficulty in greatly improving performance. Therefore, there is an urgent need for a nanoporous silicon preparation method that can solve the above problems

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