Yolk-shell structured FeS0.5Se0.5@N-doped mesoporous carbon composite as high-performance lithium-ion battery anodes

Abstract

Transition metal selenides/sulfides are drawing growing attention as promising electrode material for lithium-ion batteries owing to their larger layer spacing and weaker ionic bond compared to transition metal oxides, which are conducive to the intercalation/de-intercalation of Li ions. However, the intrinsic low conductivity and large volume expansion remain a major obstacle for their practical applications. In this work, with the prediction help of the theory model, we design a yolk-shell structure of single-phase ternary FeS0.5Se0.5 and nitrogen-doped mesopore carbon (YS-FeS0.5Se0.5@NMC) via an interfacial co-assembly, followed by one-step selenization and vulcanization. In the composite, single-phase ternary FeS0.5Se0.5 yolk provides more active sites and faster ion/electron transport dynamics than binary Fe2O3, while N-doped mesoporous carbon shell effectively alleviates the large volume expansion of FeS0.5Se0.5, as revealed by in-situ Raman analysis and TEM observation. Meanwhile, the spatial confinement of outer carbon shell also ensures the mechanical stability of the electrode during cycles. These merits endow the YS-FeS0.5Se0.5@NMC anode with a high reversible capacity of 1417mA h/g at 200mA h/g after 120 cycles, and an exceptional rate capability. This work offers an inspired approach for achieving high-performance energy storage electrode materials