Unlocking superior lithium storage via synergistic confinement: metal–organic framework-derived carbon-confined metal sulfides

Abstract

Metal–organic framework (MOF)-derived materials, such as transition metal sulfides (TMSs), are attracting much attention for their high theoretical specific capacity as anodes for lithium-ion batteries (LIBs). Herein, a core–shell-structured anode comprising a Cu₉S₅ core and a Co₃S₄ shell embedded in nitrogen-doped carbon (NC) (Cu₉S₅/NC@Co₃S₄/NC) has been developed by combining the calcination and sulphuration treatments of the Cu-BTC@ZIF-67 precursor. In this composite, both Cu₉S₅ and Co₃S₄ exhibit high electrochemical reaction activities. The sulfides were combined in situ with the porous nitrogen-doped carbon to realize an integrated structure, which efficiently alleviated their aggregation and volume variations during the charging and discharging processes. The good reactivity and structural stability of the Cu₉S₅/NC@Co₃S₄/NC anode led to a high capacity (1067.3 mAh g⁻¹ at 0.1 A g⁻¹), even at 5 A g⁻¹. The Cu₉S₅/NC@Co₃S₄/NC anode showed negligible capacity degradation and maintained a capacity of 500 mAh g⁻¹ after 500 cycles. This study proposes an effective strategy for engineering high-performance sulfide-based anodes for LIBs, as evidenced by their superior electrochemical performance.