ZIF-90 derived carbon-coated kerf-loss silicon for enhanced lithium storage

The utilization of kerf-loss silicon (KL-Si) waste as anode materials in lithium-ion batteries (LIBs) faces limitations of the rapid structural degradation during repeated charging/discharging. To overcome this limitation, 3D carbon-coated Si is constructed to buffer the Si volume expansion caused by the lithiation, while simultaneously forming a robust conductive network. Meanwhile, the well-dispersed porous carbon (C) shell, doped with suitable heteroatoms, plays a pivotal role in facilitating rapid ion transfer rates. In addition, a cobalt (Co) and nitrogen (N)-doped C shell is employed to encapsulate KL-Si, aimed at enhancing its lithium (Li) storage performances. The electrochemical performance of KL-Si@C-ZIF/N/Co composites, synthesized through the encapsulation of KL-Si with a metal-organic framework (MOF) structure (ZIF-90) followed by heat treatment. The resulting composites exhibit an outstanding reversible capacity of 981 mAh g-1 and an impressive capacity retention of 81.9% at 2 A g-1 even after 350 cycles. This paper presents a promising method for maximizing the value-added utilization of KL-Si and reveals the advantages of MOF-derived porous C shell in accommodating the inherent volume expansion of Si-based anodes.