Metal vacancies abundant Co0.6Fe0.4S2 on N-doped porous carbon nanosheets as anode for high performance lithium batteries

Abstract

Transition metal sulfides have been considered as promising anodes for lithium batteries for its high theoretical specific capacity. However, the lower conductivity, larger volume change and slower electrochemical reaction dynamics still hinder its practical applications. Here, Co0.6Fe0.4S2 nanoparticles with metal vacancies anchored on the N-doped carbon nanosheets (NC@Co0.6Fe0.4S2) are designed and fabricated by a facile hydrothermal method. The NC@Co0.6Fe0.4S2 delivers high reversible capacity, stable cyclability and excellent rate capacity by retaining the capacities of 830mAh g−1 after 100 cycles at 200 mA g−1 and 696mAh g−1 after 500 cycles at 5000 mA g−1. The improved electrochemical performance is attributed to the metal vacancies, N-doped carbon nanosheets and strong metal-nitrogen bonds between the Co0.6Fe0.4S2 and N-doped carbon nanosheets, which greatly enhance charge transfer/transport and maintain structural integrity. The construction of metal vacancies along with N-doped carbon wrapping can be extended to prepare other transition metal sulfides for enhancing the electrochemical performance.