MOF-derived N,S Co-doped carbon matrix-encapsulated Cu2S nanoparticles as high-performance lithium-ion battery anodes: a joint theoretical and experimental study

Abstract

Transitional metal dichalcogenides (TMDs) hold great potential as promising rechargeable battery anodes owing to their abundant electrochemical active sites and high specific capacity, but they still suffer from low electrical conductivity, irreversible redox reactions and sluggish electrochemical kinetics. In this study, a MOF-derived Cu₂S@N,S co-doped carbon heterostructure (Cu₂S@NSC) was fabricated, in which Cu₂S nanoparticles were uniformly embedded in a N,S–C matrix. The mechanisms of alkali metal ion (Li⁺, Na⁺ and K⁺) storage by Cu₂S@NSC were investigated by first-principles calculations based on density functional theory studies. Computations revealed that the Cu₂S@NSC electrode could possess increased electrical conductivity giving rise to a low ion diffusion barrier, which can optimize the ion adsorption behavior and significantly accelerate the charge transfer kinetics. In addition, Li-ion batteries (LIBs) were assembled based on Cu₂S@NSC anodes to verify our theoretical analysis. Benefitting from the heteroatom co-doping strategy and elaborate heterogeneous interface, the Cu₂S@NSC electrode-based LIBs exhibit a dramatically enhanced long cycling stability of 512.7 mA h g⁻¹ after 1000 cycles at 1 A g⁻¹ and a prominent rate capacity of 373.1 mA h g⁻¹ at 5 A g⁻¹. All these characteristics and theoretical calculations demonstrate the reliability of heteroatom co-doping as well as heterogeneous interface strategies. This method can be extended to analyze other TMD materials for various energy-related applications.