A new insight into capacity fading of sulfurized polyacrylonitrile composite in carbonate electrolyte

Sulfurized polyacrylonitrile (S/PAN) composite shows great potential as a cathode material for lithium sulfur batteries, due to its advantages in cycle performance and carbonate electrolyte compatibility. However, the cell using S/PAN composite as a cathode material exhibits sluggish reaction kinetics due to the low conductivity. Moreover, capacity fading is also found in long-term cycle test and the mechanism is not well studied in previous reports. In this work, a compact composite, S/PAN confined in macro-porous carbon (MaPC), is firstly prepared by using a sulfur copolymer to improve the cycle stability. The cathode shows stable cycle stability during the initial 150 cycles at the current density of 1050 mA gsulfur-1 and the capacity maintained at 806 mAh gsulfur-1 . The cycle stability is getting worse during the long-term cycle test. It is found that the capacity fading is highly related to the increasing resistance and the formation of sulfates or sulfate-like components during the repeated cycling process.

Automated summary

Sulfurized polyacrylonitrile (S/PAN) composite is considered as a promising cathode material for lithium sulfur batteries due to its advantages in cycle performance and carbonate electrolyte compatibility. However, the sluggish reaction kinetics and capacity fading caused by low conductivity remain challenges. In long-term cycle tests, the capacity fading is found to be highly related to increasing resistance and the formation of sulfates or sulfate-like components during repeated cycling processes.