High-Entropy Alloys to Activate the Sulfur Cathode for Lithium-Sulfur Batteries

Sulfur element possesses an ultrahigh theoretical specific capacity, while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products, limiting the enhancement on energy density of lithium-sulfur batteries. Herein, for the first time, Fe0.24Co0.26Ni0.10Cu0.15Mn0.25 high-entropy alloy is introduced as the core catalytic host to activate the electrochemical performance of the sulfur cathode for lithium-sulfur batteries. It is manifested that Fe0.24Co0.26Ni0.10Cu0.15Mn0.25 high-entropy alloy nanocrystallites distributed on nitrogen-doped carbon exhibit high electrocatalytic activity toward the conversion of solid sulfur to solid discharged products across soluble intermediate lithium polysulfides. In particular, benefiting from the accelerated kinetics by high-entropy alloy nanocrystallites and synergistic adsorption by nitrogen-doped carbon, the cathode exhibits high reversible capacity of 1079.5 mAh g(-cathode)(-1) (high utilization of 89.4%) with the whole cathode as active material, instead of sulfur element. Moreover, under both lean electrolyte (3 mu L mg(-1)) and ultrahigh sulfur loading (27.0 mg cm(-2)) condition, the high discharge capacity of 868.2 mAh g(-cathode)(-1) can be still achieved for the sulfur cathode. This strategy opens up a new path to explore catalytic host materials for enhancing the utilization of sulfur in the whole cathode for lithium-sulfur batteries.

Automated summary

This study introduces a high-entropy alloy as a catalytic host to activate the electrochemical performance of the sulfur cathode in lithium-sulfur batteries, enhancing the utilization of sulfur. The high-entropy alloy nanocrystallites on nitrogen-doped carbon exhibit high electrocatalytic activity, promoting the conversion of solid sulfur to soluble intermediate products and increasing the reversible capacity of the battery when the whole cathode is used as the active material.