A kind of silicon carbon negative electrode and preparation method thereof

Abstract

The invention discloses a silicon-carbon negative electrode and a preparation method thereof. The silicon-carbon negative electrode comprises a current collector, an active material layer coated on the current collector, and a functional coating coated on the active material layer; the functional coating includes a poly Pyrrole and single-wall carbon nanotubes, polypyrrole and single-wall carbon nanotubes form a three-dimensional mesh conductive network. The present invention also provides a method for preparing a silicon carbon negative electrode, comprising: (1) coating an active material layer slurry on a current collector; (2) coating a functional coating slurry on an active material layer of a current collector to obtain a silicon carbon negative electrode. The carbon negative electrode; the functional coating slurry is prepared by the following method: the pyrrole monomer is dispersed in a solution containing single-walled carbon nanotubes to prepare the functional coating slurry; during the reaction, the pyrrole monomer is polymerized to form polypyrrole, Polypyrrole and single-walled carbon nanotubes form a three-dimensional mesh-like conductive network. The silicon-carbon negative electrode of the invention suppresses the volume expansion of the silicon-carbon negative electrode of the silicon-based lithium ion battery, and improves the conductivity of the silicon-carbon negative electrode.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a silicon carbon negative electrode and a preparation method thereof. Background technique [0002] Lithium-ion batteries have the advantages of no memory effect, small self-discharge, high voltage, long cycle life, and environmental friendliness. Most of the existing commercial lithium-ion batteries use graphite as the negative electrode material, but their theoretical electrochemical lithium storage capacity is only 372mAh / g, which is far from meeting the needs of lithium-ion batteries to further increase the energy density. Compared with graphite anode materials, silicon-based anode materials have obvious advantages in energy density, and their theoretical specific capacity can be as high as 4200mAh / g. Due to their abundant reserves and low lithium intercalation potential, silicon-based anode materials have become a hotspot in the research and application of ano...

AI Technical Summary

Problems solved by technology

However, there are many problems to be solved urgently in the practical application of silicon-based negative electrode materials. The main manifestations are: the volume effect of silicon in the process of intercalation and delithiation is large, and the high volume expansion rate makes silicon particles pulverize severely and decay rapidly during the cycle; secondly , silicon is a semiconductor, and its conductivity is much worse than that of graphite anode, which greatly affects the first coulombic efficiency and high-current charge-discharge capability of silicon-based lithium-ion batteries.

In short, the existing silicon-based lithium-ion batteries have the problems of large volume expansion rate of silicon-carbon negative electrodes and poor electrical conductivity.

Images