Graphene-based nitrogen-doped hierachical-pore carbon nanosheet/sulfur composite material for cathode of lithium sulfur battery, as well as preparation method and application of graphene-based nitrogen-doped hierachical-pore carbon nanosheet/sulfur composite material

Abstract

The invention discloses a graphene-based nitrogen-doped hierachical-pore carbon nanosheet / sulfur composite material for a cathode of a lithium sulfur battery, as well as a preparation method and application of the graphene-based nitrogen-doped hierachical-pore carbon nanosheet / sulfur composite material. The carbon nanosheet is a graphene-based nitrogen-doped hierachical-pore carbon nanosheet, and is prepared by the steps of growing poly-pyrrole on graphene oxide in situ, performing carbonization at high temperature, activating by using potassium hydroxide and forming pores, wherein the graphene oxide and nano-silicon dioxide serve as double templates; the thickness of the carbon nanosheet is 10 to 25 nm; the specific surface area is 800 to 1,600 m<2> / g; the pore diameter of the carbon nanosheet is distributed into the range of 0.8 to 6 nm in a concentrated way; the structure of the carbon nanosheet is a sandwich-like type which adopts graphene as the interlayer of the carbon nanosheet. The carbon nanosheet with abundant micro-pores, meso-pores and large specific surface area can load more sulfur active substances and can effectively inhibit dissolution of polysulfide. The ultrathin nanosheet, and the micro-pores and meso-pores guarantee diffusion of electrolyte and transmission of ions. According to the structure, the capacity, the cycling stability, the coulombic efficiency and the rate performance of the carbon nanosheet / sulfur composition material applied to the lithium sulfur battery are improved synergistically.

Description

technical field [0001] The invention belongs to the field of electrochemical energy and nanometer materials, and relates to a preparation method and application of key positive electrode materials for lithium-sulfur secondary batteries, in particular to a graphene-based nitrogen-doped hierarchical porous carbon nanosheet / sulfur composite for positive electrodes of lithium-sulfur batteries Materials and their preparation methods and applications. Background technique [0002] The rapid development of current communication, portable electronic equipment, electric vehicles and space technology urgently requires the development of batteries with higher energy density. At present, although the laboratory specific energy of lithium-ion batteries has reached 250Wh kg -1 , but limited by the further improvement of the specific capacity of the positive electrode material, it is difficult to increase the specific energy, and the way of increasing the specific energy by increasing the...

AI Technical Summary

Problems solved by technology

However, the small pore volume of microporous carbon limits the assembly of sulfur nanoparticles, resulting in a low overall battery capacity and discharge platform, which affects the energy density of the overall battery.

In summary, although the research on lithium-sulfur secondary batteries has achieved many breakthroughs, it is not difficult to find that many studies only address a certain problem and ignore other problems.

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