A kind of preparation method of nanoscale silicon negative electrode of lithium ion battery

Abstract

The invention discloses a preparation method of a nanometer silicon negative electrode for lithium ion batteries, and relates to the lithium ion batteries. The nanometer silicon negative electrode for the lithium ion batteries is a silicon @ hole @ carbon structure silicon negative electrode, and an initiator is grafted on the surface of a silicon ball through surface modification to obtain an initiator grafted silicon ball; the obtained initiator grafted silicon ball grafts a polymer which can be completely thermally decomposed as a medium layer through active free radical polymerization; a carbon clad layer is clad on the surface layer of an obtained sample as a carbon layer precursor; the obtained sample is oxidatively cross-linked in an air atmosphere and is thermally decomposed in an inert atmosphere, the medium layer is completely decomposed to obtain a silicon expanded hole space, and the carbon layer precursor is thermally decomposed and carbonized to obtain shell carbon, so that the nanometer silicon negative electrode for the lithium ion batteries is obtained. The preparation method is effectively combined with an active free radical polymerization process with relatively high controllability. Different carbon sources can be regulated, controlled and used. The operation controllability is high, and the expansion space of the silicon ball and the thickness of the carbon layer can be effectively adjusted. The operation process is easy to perform, little in dangerousness and easy for amplification.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to a preparation method of a nanoscale silicon negative electrode of a lithium ion battery. Background technique [0002] With the development of science and technology and economy, high-performance electronic devices and electric vehicles emerge in an endless stream. However, the lithium-ion battery with graphite negative electrode (theoretical capacity 370mA h / g) commonly used in the market cannot meet the requirements of high capacity and low cycle loss. Therefore, it is necessary to design electrode active materials with better performance, such as: Si, Ge, SnO 2 , SiOC and so on. In continuous research, it is found that the theoretical capacity of Si is very high, about 10 times that of graphite (when forming an alloy with Li, Li 15 Si 4 The capacity is 3579mA·h / g), and it has a low lithiation / delithiation potential, so it has attracted widespread attention in the industry. However,...

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Problems solved by technology

[0007] To sum up, it can be seen that in order to obtain a buffer space sufficient for the volume expansion of silicon during the lithiation process, the skeleton structure can be designed, the reduction of silicon dioxide, or the etching of silicon dioxide, etc., but in the process of consulting the literature, there is no Articles that use polymer pyrolysis to obtain this buffer space are found. Because most linear polymers have extremely low carbon residue rate or even 100% decomposition during the pyrolysis process, the polymer introduces silicon cores and The middle of the shell carbon precursor layer is used as a medium layer. When the carbon layer is prepared by pyrolysis, the carbon layer precursor is pyrolyzed and converted into a carbon shell layer, and at the same time, the polymer medium layer filled between the silicon core and the carbon precursor is decomposed to obtain Expansion space of silicon spheres

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