Encapsulation of Cu2S with a nitrogen-doped carbon boosts Na+ storage with a reversible Na2S conversion reaction
Zulkifli, Seungbok Lee, Ghalib Alfaza, Ahmad Nurul Fahri, Balaji Sambandam, Vincent Mathew, Seungbok Lee, J. Park, Min‐Kyu Song, Jong‐Hyeon Lee, Jang‐Yeon Hwang, J. Kim
Abstract
The high reversibility of a conversion-anode material enables high reversible capacity and maintains its cyclability. In this work, we report copper sulfide microspheres encapsulated by nitrogen-doped carbon (Cu 2 S@NC) prepared via a conventional polyol process and demonstrate their potential use as anode materials for sodium-ion batteries. Nitrogen-doped carbon stimulates a reversible conversion reaction of Cu 2 S + Na ↔ Na 2 S + Cu while corroborating the phase stability, leading to excellent Na + storage properties of the Cu 2 S@NC. Thus, the Cu 2 S@NC anode demonstrates an excellent cyclability of 284.99 mA/h/g at a higher current at 5000 mA/g. Operando X-ray diffraction and density functional theory calculations are combined to verify the electrochemical Na + storage mechanism of the Cu 2 S@NC.