Electrostatic self-assembling preparation method of graphene/silicon electrode material

Abstract

The invention provides an electrostatic self-assembling preparation method of graphene / silicon electrode material. The preparation method comprises the following steps: performing full-carbon surfaceoxidation on high-quality graphene by using potassium permanganate and like oxidants to obtain a graphene oxide material with oxygen-containing groups uniformly distributed on the surface of graphenelamella; etching oxide on the silicon particle surface by using hydrofluoric acid, performing charge modification on the nano silicon by using hexadecyl trimethyl ammonium bromide, thereby enabling the nano silicon particles to possess positive charge, and the accomplishing the electrostatic self-assembling with the graphene oxide; preparing an independent self-support film by using a vacuum filtration method, reducing through the hydroiodic acid under the room temperature to obtain the composite electrode material. The oxygen-containing groups on the surface of the graphene oxide material areuniformly distributed, and can be uniformly compounded with the nano silicon particles with the positive charge in the electrostatic self-assembling process, the volume effect of the silicon in the circulation process is inhibited, thereby preventing the silicon from directly contacting the electrolyte, the irreversible capacity is reduced, and the rate performance of the silicon-based material is improved.

Description

technical field [0001] The invention relates to the field of graphene / silicon composite electrode material preparation. Background technique [0002] In recent years, lithium-ion batteries have been widely used in notebook computers, mobile phones, Ipads, electric vehicle power supplies and other products. In the efficient and convenient information age, the important role of lithium-ion batteries has been irreplaceable. As an anode material, the theoretical lithium storage capacity of silicon is as high as 4200mAhg -1 , much higher than commercial graphite (375mAhg -1 ), its low discharge potential can increase the output voltage of the battery, and the longer discharge platform can ensure a stable output voltage, so silicon is an ideal lithium battery negative electrode material. [0003] Due to the problem of large volume changes in the silicon material during charging and discharging, the electrode powders and falls off as the cycle progresses, resulting in rapid capac...

AI Technical Summary

Problems solved by technology

However, because the conductivity of graphene oxide is far from that of intrinsic graphene, the performance of silicon / graphene composite electrode materials needs to be improved; Chou et al. used mechanical grinding to mix nano-silicon and graphene obtained by solvothermal method. A silicon / graphene composite material was obtained, and its initial discharge capacity and Coulombic efficiency were 2158mAh·g, respectively. -1 and 73%, after 30 cycles, the reversible capacity remained at 1168mAh g -1

The good mechanical properties and electrical conductivity of graphene can relieve the deformation stress of silicon and provide good electrical conductivity. However, simple mechanical mixing is difficult to disperse nano-silicon particles uniformly between graphene layers, thus limiting the further development of its performance. promote

Ji et al. used the method of plasma-enhanced chemical vapor deposition to prepare a multi-level silicon / graphene composite film, which has a much higher capacity than pure silicon film electrodes. The deposited graphene thin layer can not only buffer the volume expansion and contraction of silicon, Moreover, the silicon layers are isolated to avoid the agglomeration of silicon. In addition, the excellent conductivity of graphene improves the conductivity of the electrode, which is conducive to the transmission of electrons and lithium ions. However, this method requires high equipment requirements, high cost, and high cost. , complex process

Images