Facile approach to thin polypyrrole encapsulation of lamellar iron (II) selenide with much improved performance for lithium-ion storage

Abstract

A facile approach is developed to fabricate polypyrrole-encapsulated lamellar iron (II) selenide (FeSe/PPy) by directly exposing FeSe to pyrrole atmosphere at room temperature. A high FeSe loading of 97 wt.% is achieved for the FeSe/PPy composite, which is designed as an anode for lithium-ion battery (LIB) with much enhanced electrochemical performance than that of the FeSe sample. The FeSe/PPy electrodes demonstrate a reversible discharge capacity of 274 mAh g[Formula: see text] after 50 cycles at a high current density of 0.5 A g[Formula: see text], whereas the lower discharge capacity of 124 mAh g[Formula: see text] for the FeSe electrodes. The FeSe/PPy electrodes also deliver greater rate capability compared to the FeSe electrodes. The improved electrochemical performance should be assigned to the contributions of fast charge transfer and structural defense from the encapsulated PPy. Hence, the FeSe/PPy composite could serve the purpose for constructing reliable anode for LIB, and the simple method of PPy coating can also be used to build high-performance electrodes for other battery systems.