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

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.