High-performance lithium-sulfur battery based on porous N-rich g-C_(3)N_(4) nan-otubes via a self-template method

The commercial development of lithium-sulfur batteries(Li-S)is severely limited by the shuttle effect of lithium polysulfides(LPSs)and the non-conductivity of sulfur.Herein,porous g-C_(3)N_(4) nanotubes(PCNNTs)are synthesized via a self-template method and utilized as an efficient sulfur host material.The one-dimensional PCNNTs have a high specific surface area(143.47 m^(2)·g^(-1))and an abundance of macro-/mesopores,which could achieve a high sulfur loading rate of 74.7wt%.A Li-S battery bearing the PCNNTs/S composite as a cathode displays a low capacity decay of 0.021% per cycle over 800 cycles at 0.5 C with an initial capacity of 704.8 mAh·g^(-1).PCNNTs with a tubular structure could alleviate the volume expansion caused by sulfur and lithium sulfide during charge/discharge cycling.High N contents could greatly enhance the adsorption capacity of the carbon nitride for LPSs.These synergistic effects contribute to the excellent cycling stability and rate performance of the PCNNTs/S composite electrode.

Preparation of CoO/SnO_(2)@NC/S composite as high-stability cathode material for lithium-sulfur batteries

To improve the sulfur loading capacity of lithium-sulfur batteries(Li-S batteries)cathode and avoid the inevitable“shuttle effect”,hollow N doped carbon coated CoO/SnO_(2)(CoO/SnO_(2)@NC)composite has been designed and prepared by a hydrothermal-calcination method.The specific surface area of CoO/SnO_(2)@NC composite is 85.464 m2·g^(-1),and the pore volume is 0.1189 cm3·g^(-1).The hollow core-shell structure as a carrier has a sulfur loading amount of 66.10%.The initial specific capacity of the assembled Li-S batteries is 395.7 mAh·g^(-1) at 0.2 C,which maintains 302.7 mAh·g^(-1) after 400 cycles.When the rate increases to 2.5 C,the specific capacity still has 221.2 mAh·g^(-1).The excellent lithium storage performance is attributed to the core-shell structure with high specific surface area and porosity.This structure effectively increases the sulfur loading,enhances the chemical adsorption of lithium polysulfides,and reduces direct contact between CoO/SnO_(2) and the electrolyte.