Binder-free porous silicon/carbon composite electrode and application thereof

Abstract

The invention discloses a binder-free porous silicon / carbon composite electrode and an application thereof. The composite electrode is prepared by the following steps of (1) mixing absolute ethyl alcohol, nitrate or perchlorate water solution and silicate alkyl ester, then adjusting pH to 2.0-6.0, and stirring to obtain a precursor solution; (2) performing surface oxide removing and oil removing on a copper foil substrate or a nickel foil substrate; (3) taking the processed copper coil substrate or the nickel foil substrate as working electrodes, and putting the working electrodes in an electrode groove loaded with the precursor solution, and taking a platinum sheet or graphite as a counter electrode to carry out electro-deposition to obtain a micro-nano silicon oxide coating on the surface of the copper coil substrate or the nickel foil substrate; (4) carrying out magnesiothermic reduction on the copper coil substrate or the nickel foil substrate coated with the micro-nano silicon oxide coating to obtain a copper foil or a nickel foil with a porous silicon-based material on the surface; and (5) carrying out chemical vapor deposition on the copper foil or the nickel foil with the porous silicon-based material on the surface to obtain the binder-free porous silicon / carbon composite electrode. The porous silicon / carbon composite electrode can be applied to the negative electrode of a lithium ion battery.

Description

(1) Technical field [0001] The invention relates to a binder-free porous silicon / carbon composite electrode and its application as a lithium ion battery negative electrode. (2) Background technology [0002] Lithium-ion batteries play an important role in people's daily life, and can be seen everywhere in the fields of communication equipment, electronic instruments, and vehicles. With the advancement of technology, the rapid development of electrical equipment has put forward higher requirements on the performance of lithium-ion batteries, but in fact, industrialized lithium-ion batteries have not made substantial breakthroughs in terms of performance stability and specific capacity. At present, commercially available lithium-ion batteries generally use graphite (theoretical specific capacity 372mAh / g) as the negative electrode material of the battery. Although graphite anode material has a stable charge-discharge platform and excellent cycle performance, it is still diffi...

AI Technical Summary

Problems solved by technology

In this process, the combination of the active conductive material graphite and silicon dioxide with the help of a binder has a great impact on the performance of the electrode in the later stage. On the one hand, if the binder is added too little, the binding force between graphite and silicon dioxide If it is too small, the volume expansion caused by delithiation and intercalation of lithium usually causes the active components to fall off from the surface of the current collector, making the electrode performance deteriorate rapidly; on the other hand, if the binder is added too much, because the binder itself is not conductive, As a result, the overall conductivity of the silicon-based composite material is not significantly improved, which seriously affects the performance of the electrode

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