Lithium battery silicon-carbon negative electrode plate and preparation method thereof

Abstract

The invention relates to a lithium battery silicon-carbon negative electrode plate and a preparation method thereof. The negative electrode plate has the characteristics of high specific capacity, good first charge-discharge efficiency, high cycling stability and the like. Under the conditions that the specific capacity is 450-700 mAh / g, the first coulombic efficiency is 83-88% and the charge-discharge rate is 0.2 C, the capacity retention rate after 100 cycles can reach 86-92%. The silicon-carbon negative electrode plate disclosed by the invention is composed of slurry coated on a copper foil, wherein the slurry comprises silicon-carbon powder, a conductive agent and a binder; nano-scale silicon powder or micron-scale silicon monoxide, graphite and organic cracked carbon are subjected to ball milling and sintering to prepare silicon carbon powder, the conductive agent is conductive carbon black and carbon nanotubes, the binder is sodium carboxymethyl cellulose and butadiene styrene rubber, and a proper amount of lauryl sodium sulfate is added as an additive to enhance the bonding effect. The preparation method is simple, the raw materials are easy to obtain, the specific capacity is improved, the volume expansion effect of the silicon material in the charging and discharging process is effectively relieved and inhibited, the cycling stability is improved, and the service life is prolonged.

Description

Technical field [0001] The invention involves the field of battery technology, especially a lithium battery silicon carbon negative film and its preparation method. Background technique [0002] With the booming development of the new energy industry, especially the promotion and use of electric vehicles, people have put forward higher requirements for the energy density, service life, and safety of lithium batteries.Most of the existing commercial lithium batteries use graphite as the negative electrode material. However, the theoretical ratio of graphite negative is only 372 mAh / g, and its actual capacity is very close to its theoretical value, and it becomes very difficult to further improve.Compared with graphite, silicon has a very high theoretical compared capacity (4200 mAh / g) and a lower voltage platform (~ 0.4V vs li / li + ) It is a very promising new type of negative material. [0003] However, as a negative electrode material in the process of completely dehydration, it...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a lithium battery silicon carbon negative electrode sheet and its preparation method, to reduce the problem that conventional silicon-based negative electrode materials are easy to pulverize due to excessive volume expansion, thereby prolonging the service life of the battery, and having High first coulombic efficiency and specific capacity