Structural Modification Engineering of Si Nanoparticles by MIL‐125 for High‐performance Lithium‐ion Storage

Abstract Si‐based anode electrodes stand out for its excellent capacity among the numerous anode electrodes for lithium‐ion batteries. However, there is still a problem that the volume expansion from the alloying reaction of Li and Si often leads to structural collapse and rapidly capacity degradation. Here, Si nanoparticles (Si NPs) are coated via metal‐organic frameworks (MOFs) derived skeleton to buffer its volume expansion, thereby improving electrochemical properties. Scanning electron microscopy was applied to revealed morphology and structure of the composite material. The results demonstrate that the structure of the prepared composite is Si NPs encapsulated in the unique carbon skeleton. The as‐prepared Si@MIL‐125‐500 exhibits excellent electrochemical performances with an excellent reversible capacity of 304.3 mAh g −1 at 5 A g −1 even after 400 cycles. In addition, the initial coulombic efficiency (ICE) reached up to 86 %. The improved electrochemical performance could be attributed to the distinctive structure of the carbon coated Si NPs and stable titanium(IV) center site, which has improved the electrical conductivity and cycling stability of Si NPs. Moreover, the empty space inside the MOF's carbon skeleton can release the volume strain of Si during electrochemical process. There is an improvement of electrochemical properties for LIBs due to Si NPs restricted in MIL‐125.