Scientists develop high-performance lithium-sulfur batteries

Recently, research groups led by Prof. Liu Jian and Prof. Wu Zhongshuai from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences have developed Fe_1-xS-decorated mesoporous carbon spheres as the nanoreactor for a lithium-sulfur battery cathode. The nanoreactor showed excellent polysulfide catalytic activity and cyclic stability. The study was published in Advanced Energy Materials on Apr. 16.

Lithium-sulfur batteries have a high theoretical energy density of 2600 Wh kg^-1 and theoretical capacity of 1675 mAh g^-1. However, the slow conversion reaction dynamics of sulfur in the process of charging and discharging lead to low utilization rate of sulfur and a serious shuttle effect. This further reduces the capacity and stability of lithium-sulfur batteries.

Therefore, a reasonably designed electrocatalytic system would realize steady and efficient catalytic transformation of polysulfide under high sulfur loading, resulting in high cyclic stability. In the current study, the researchers designed a mesoporous carbon nanoreactor decorated with highly dispersed Fe_1-xS electrocatalyst nanoparticles (Fe_1-xS-NC), and applied it as a lithium-sulfur battery cathode for high catalytic activity and high sulfur loading.

The nanoreactor has low mass density, high porosity, and a highly dispersed electrocatalyst, which significantly improves the adsorption and catalytic conversion capacity of polysulfides. The researchers found that there was virtually no decay in capacity of Fe_1-xS-NC from an initial value of 1070 mAh g^-1 after 200 cycles and under a current density of 0.5 C.

"The nanoreactor design strategy provides a new protocol for building high-capacity and long-cycle rechargeable batteries," said Prof. Liu. "It will also open an avenue for design of safer and high-energy-density Li-metal batteries."