Uncover the Effective Confinement of Lithium-Polysulfides and Enhanced Reaction Kinetics of Sulfur on Monoxide@Carbon Hollow Nanospheres
Update: 2017-03-02 15:05:53      Author: yangjuan@csrc.ac.cn

Lithium-sulfur (Li-S) batteries exhibit great advantages for next generation electrical energy storage and conversion due to their high theoretical energy density, low cost and environmental friendliness. However, the commercialization of the rechargeable Li-S battery is still hindered by several issues such as the inherent poor electronic conductivity of sulfur and its discharge products (Li2S/Li2S2), the dissolution of intermediate lithium polysulfides (LiPSs), as well as the large volumetric expansion upon full lithiation. Thus, it is vital to enhance the conductivity of the sulfur cathode and moderate the dissolution of lithium polysulfides for the application of lithium-sulfur batteries.

A group at CSRC, led by Dr. Li-Min Liu, has worked together with Prof. David Lou’s group at Nanyang Technological University, and they discovered a new sulfur host based on highly conductive polar TiO@C hollow nanospheres for lithium-sulfur batteries. This host can maximize the effectiveness of moderating LiPSs diffusion and enhance the redox reaction kinetics of sulfur species at the same time. The extensive first-principles calculations and the experiments indicate that titanium monoxide@carbon hollow nanospheres with inherent metallic conductivity and strong adsorption capability for lithium-polysulfides can not only generate sufficient electrical contact to the insulating sulfur for high capacity, but also effectively confine lithium-polysulfides for prolonged cycle life. This work overcomes the major limitations associated with other polar and nonpolar sulfur hosts, and may open up the prospect of constructing more efficient nanostructures for moderating the diffusion of LiPSs and enhancing the reaction kinetics of sulfur.

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Fig. 1. (a) Synthesis process of the TiO@C-HS/S composite. (b) The optimized geometries for the interaction between Sx and Li2Sx (x = 1, 2 and 4) on TiO (001) surfaces. (c)-(d) Isosurface of the charge density difference for (c) S and (d) Li2S adsorbed on TiO (001).

 

For more information, please see the paper “A sulfur host based on titanium monoxide@carbon hollow spheres for advanced lithium-sulfur batteries” Zhen Li, Jintao Zhang, Buyuan Guan, Da Wang, Li-Min Liu*, Xiong Wen (David) Lou*, Nature Commutations, 7, 13065 (2016).


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