Double bond effects induced by iron selenide as immobilized homogenous catalyst for efficient polysulfides capture

Abstract

• A double bond effect based on selenide was introduced into Li-S batteries. • FeSe was applied as a host in Li-S battery for the first time. • The catalytic effect of FeSe@NC on solid–solid conversion is analyzed. The low utilization of sulfur and the shuttle effect accompanying the discharge process are the fundamental problems that hinder the development of lithium-sulfur (Li-S) batteries. Although the LiPSs loss and conversion are ameliorated by physical and chemical methods with the design of multi-functional host material structures, the problem of capacity attenuation has not been fundamentally solved. Seeking for reliable polar hosts with suitable adsorption capacity and good catalytic ability for the conversion process is still an issue with great challenge. Herein, a high-efficiency nitrogen doped carbon supported FeSe electrocatalyst derived from the carbon skeleton (FeSe@NC) is used as the sulfur host for Li-S batteries. During the discharge process, Fe-S and Li-Se bonds would be formed in pairs, thus forming a double bond effect to alleviate the shuttle effect. In particular, the FeSe@NC with good conductivity and double bond effect can catalytically accelerate capture/diffusion of polysulfides and improve the utilization of active substances from Li 2 S 2 to Li 2 S in solid-to-solid conversion. Thus, the FeSe@NC/S cathode exhibits an excellent capacity of 1087 mAh g −1 at 1C and 441 mAh g −1 at 5C. This work will inspire the optimization design of adsorption-electrocatalysis engineering of transition-metal-based composite materials for diverse applications.