SnO2/graphene composite material as well as preparation method and application thereof

Abstract

The invention discloses a SnO2 / graphene composite material as well as a preparation method and application thereof, and belongs to the technical field of new energy materials. The preparation method comprises the steps of taking a metal Sn foil as a target material and deionized water as a solvent, and preparing a SnOx colloidal solution by adopting a liquid-phase pulse laser irradiation technology; and dropwise adding the SnOx colloidal solution into the graphene oxide solution, uniformly mixing and dispersing, carrying out hydrothermal reaction, and carrying out freeze drying on the productto obtain a SnO2 / graphene composite material. According to the SnO2 / graphene composite material prepared by the invention, SnOx and graphene oxide are subjected to an in-situ oxidation-reduction reaction in a hydrothermal process, so that uniform and tight anchoring of covalent bonding of ultrafine SnO2 quantum dots on a reduced graphene oxide lamellar wall is realized; and the porous structure ofthe reduced graphene oxide can also be maintained when SnO2 quantum dots are highly loaded.

Description

technical field [0001] The invention belongs to the technical field of new energy materials, in particular to a SnO 2 / Graphene composite materials and their preparation methods and applications. Background technique [0002] As a green, safe and efficient energy storage device, lithium-ion batteries have been widely used in the field of portable electronic devices. At present, commercial lithium-ion batteries mostly use graphite as the negative electrode material, but its theoretical capacity is only 372mAh g -1 , It is difficult to meet the high energy and high power requirements of electric vehicles, high-end electronic products and large-scale energy storage networks. [0003] Tin dioxide (SnO 2 ) due to the high theoretical capacity (1494mAh g -1 ), low lithium intercalation potential, and low price are regarded as the most promising anode materials for next-generation lithium-ion batteries. But it has three outstanding defects: (1) SnO 2 The intrinsic conductivi...

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Problems solved by technology

But it has three outstanding defects: (1) SnO 2 The intrinsic conductivity is very low, which seriously hinders the charge transport and reaction kinetics in the electrochemical process, resulting in poor battery rate performance; (2) SnO in the process of lithium ion intercalation and alloying 2 The volume expansion of the active material is as high as 400%, resulting in serious agglomeration or even pulverization of the active material, and the rapid decline of the battery capacity; (3) The drastic volume change during the charging and discharging process leads to the continuous formation, decomposition and consumption of the solid electrolyte interlayer (SEI). Lithium ions in the electrolyte, resulting in a decrease in Coulombic efficiency

But adopt this kind of method to have following defect: (1) prepared SnO 2 The particle size is still large, unevenly distributed and cannot be tightly anchored on the graphene substrate; (2) additional chemical reagents (such as HCl, NaBH 4 or hydrazine hydrate, etc.), not only harmful to the environment, but also pollute SnO 2 Particle surface is not conducive to lithium ions in SnO 2 Transport in particles; (3) SnO 2 The loading amount is limited, too high loading amount will reduce the specific surface area of ​​the composite material, and destroy the structural stability of the electrode during cycling.

The above structural defects lead to SnO 2 / Graphene-based lithium-ion battery performance is still unsatisfactory

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