Core–shell Cu_1−x NCo_3−y /a-CuFeCo antiperovskite as high-performance anode for Li-ion batteries

Abstract

Currently, there is an emergent interest in the antiperovskite family of materials in the context of energy applications in view of their distinct and peculiar set of structural and electronic properties. This work examines the surface-modified antiperovskite nitride CuNCo3 as a high-performance anode material for Li-ion storage devices. The antiperovskite CuNCo3 was prepared by the hydrothermal method followed by calcination in the NH3 atmosphere. An amorphous layer on the surface of CuNCo3 (Cu1-xNCo3-y/a-CuFeCo) was also fabricated to enhance its performance as an anode material for Li-ion batteries. The surface-modified Cu1-xNCo3-y/a-CuFeCo material was noted to deliver an extraordinarily high reversible capacity of ~1150 mAh g-1 at a current density of 0.1 A g-1, whereas the CuNCo3 showed a reversible capacity of ~408 mAh g-1 at the same current density. The initial capacity of Cu1-xNCo3-y/a-CuFeCo exhibited excellent retention (>62%) even after 350 cycles. A ~ 6 nm thin amorphous layer around the surface of pure CuNCo3 helped almost double the specific capacity as compared to the pure CuNCo3 due to the presence of a multi-redox centre for Li-ion to react and also concomitantly improved electrical conductivity property. The cyclic stability of the Cu1-xNCo3-y/a-CuFeCo material at a higher current density (0.5 and 1.0 A g-1) was also noticeable. This work opens up new materials routes and promising processing strategies to develop high reversible capacity anodes for alkali ion batteries.