Three-dimensional selenium/graphene foam meshed porous self-supporting flexible electrode material, preparation method and application

Abstract

The invention belongs to the technical field of electrode materials, in particular relates to a three-dimensional selenium / graphene foam meshed porous self-supporting flexible electrode material, a preparation method and an application. The three-dimensional selenium / graphene foam meshed porous self-supporting flexible electrode material is prepared by using a simple chemical vapor deposition technique and an impregnation method. The obtained positive electrode material is composed of elemental selenium and graphene foams; the elemental selenium is an active substance and is coated in the graphene foams to provide an active site; the electrical conductivity of the composite material is improved by the graphene foams so as to alleviate the shuttle of polyselenides; the synergistic action ofthe two components makes the self-supporting flexible electrode material exhibit high capacity and high cycle stability. The chemical vapor deposition technique and the impregnation method utilized by the invention are easy and effective, and the large-scale preparation and low-cost industrialization of the three-dimensional selenium / graphene foam meshed porous self-supporting flexible electrodematerial are easily realized.

Description

Technical field [0001] The invention belongs to the technical field of electrode materials, in particular to a three-dimensional selenium / graphene foam network porous self-supporting flexible electrode material, a preparation method and an application. Background technique [0002] The development of an advanced energy storage system with high energy density, long cycle performance, low consumption and low cost has become a worldwide research topic. High-energy-density batteries can be used in all-electric engines and hybrid engines. The current commercial batteries can generally reach a mass specific capacity of 120-160mAh / g, which is far lower than the current demand for energy applications. Lithium-sulfur batteries have attracted attention due to their high theoretical energy density (2570Wh / kg) and volumetric energy density (2200Wh / L). However, sulfur as a battery cathode material has always faced two urgent problems: one is the extremely poor conductivity of sulfur, which l...

AI Technical Summary

Problems solved by technology

However, sulfur, as a cathode material for batteries, always faces two problems that need to be solved urgently: one is the extremely poor conductivity of sulfur, which leads to low active material utilization and rate performance; The polysulfides in the lithium-sulfur electrolyte can be dissolved in the lithium-sulfur electrolyte, that is, the shuttle effect, so during the cycle, due to the shuttle effect, the active material of the sulfur cathode is greatly lost, and the capacity also decreases rapidly.

The negative impact of the shuttle effect on the electrochemical performance of the battery is as follows: (1) polyselenium ions corrode the negative electrode, destroy the SEI film, consume the electrolyte, and reduce the Coulombic efficiency of the battery; (2) the surface of the negative electrode is continuously deposited and covered with poorly conductive Se and Li 2 Se, the internal resistance and polarization of the battery continue to increase; (3) During the cycle, lithium polyselenide dissolves and migrates continuously, deactivating some active materials, resulting in low utilization of active materials; (4) The shuttle effect will also Causes the battery to self-discharge during storage

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