Nanometer titanium dioxide composite nitrogen-doped carbon nanofibers and preparation method and application thereof

Abstract

The invention discloses nanometer titanium dioxide composite nitrogen-doped carbon nanofiber and a preparation method and application thereof. The nanofibers are prepared by the following steps: S1. preparing a DMF precursor solution of polyacrylonitrile; 2, uniformly mixing tetrabutyl titanate and the precursor solution to obtain an emulsion; and 3, electrospinning the emulsion to obtain precursor fibers; then performing pyrolysis and carbonization on the precursor fibers to obtain the nanofibers. The surface of the nano fiber provided by the invention is a balsam pear-shaped fold, and afterbeing prepared as a positive electrode of a lithium sulfide battery, the conductivity of the sulfide positive electrode can be improved and the lithium polysulfide shuttle effect can be reduced; Because of its unique three-dimensional self-supporting balsam pear fiber structure, it not only increases the adsorption sites of lithium polysulfide, but also greatly alleviates the volume expansion of the battery. 97% capacity can be maintained after 100 cycles at 0.2 C current density after the nanofibers are made into a three-dimensional self-supporting current collector, and the nanofibers have stable cycling performance and high specific capacity.

Description

technical field [0001] The invention relates to the technical field of lithium-sulfur batteries, and more specifically relates to a nano-titanium dioxide composite nitrogen-doped carbon nanofiber and a preparation method and application thereof. Background technique [0002] Due to the impact of the energy crisis and the concept of green development, energy storage devices with high specific capacity and long cycle life have received more and more attention. Lithium-sulfur batteries have a high energy density (2600 W h kg -1 ) and high specific capacity (1675mAh g -1 ) is considered to be one of the next-generation low-cost secondary batteries that can replace lithium-ion batteries. [0003] The current research on lithium-sulfur batteries has gone through many years. Although many achievements have been made and a deeper understanding of its reaction mechanism has been obtained, there are still problems that are difficult to solve. These problems are mainly divided into ...

AI Technical Summary

Problems solved by technology

[0003] At present, the research on lithium-sulfur batteries has gone through many years. Although many achievements have been made and a deeper understanding of its reaction mechanism has been obtained, there are still problems that are difficult to solve.

These problems are mainly divided into two aspects: (1) in the cathode region, the insoluble and insulating S and Li 2 S will lead to slow battery reaction kinetics, and will destroy the structure of the positive electrode material of the battery, resulting in volume expansion of the positive electrode material

(2) The shuttle effect of lithium polysulfide (Li2Sn, n=4,6,8) will lead to the loss of active materials, which will lead to the reduction of capacity performance and Coulombic efficiency of the battery, the consumption of electrolyte and the corrosion of lithium negative electrode

The commonly used current collector is aluminum foil, but when aluminum foil is used as a current collector, side reactions will occur during the battery reaction and by-products will be generated, which will affect the performance of the battery.

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