"Efficient synthesis of high-sulfur-content cathodes for high-performance Li–S batteries based on solvothermal polysulfide chemistry"

Yu-Ting Weng: Hansen Wang, Rung-Chuan Lee, Ching-Yu Huang, Sheng-Siang Huang, Mozaffar Abdollahifar, Li-Ming Kuo, Bing-Joe Hwang, Chin-Lung Kuo, Yi Cui, Nae-Lih Wu; Journal of Power Sources, 01/05/20.

Additional Authors: Hansen Wang, Rung-Chuan Lee, Ching-Yu Huang, Sheng-Siang Huang, Mozaffar Abdollahifar, Li-Ming Kuo, Bing-Joe Hwang, Chin-Lung Kuo, Yi Cui, Nae-Lih Wu

Abstract:

A novel solvothermal polysulfide (PS) chemistry enables a facile and highly efficient process for synthesizing sulfur-carbon (S–C) composite powders containing up to 90 wt% S for high-performance Li–S batteries. Molecular dynamics calculations and experimental analyses reveal the formation of PSs upon dissolution of elemental S in N-methyl-2-pyrrolidone (NMP) at elevated temperatures and efficient infiltration of the PSs into the carbon host driven by the strong coupling with the C surfaces. The coupling enables extensive contact between S and C in the composite, leading to promising electrochemical properties for Li–S battery applications. In the power-type configuration, the composite cathodes having medium-to-high S contents (55 and 75%) demonstrate stable capacity at high current densities up to 100C (1C ¼1670 mA g 1-S) and no capacity fade up to 1000 cycles at 2C. In the energy-type configuration, a high-S-content and high-loading (90%-S, 4.2 mAh cm 2) cathode shows a specific capacity of 1440 mAh g 1 (86% S utilization) and 90% capacity retention after 300 cycles. This synthesis method enables significant advancement in realizing large-scale applications of Li–S batteries.

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