On the rising extra storage capacity of ultra-small Fe3O4 particles functionalized with HCS and their potential as high-performance anode material for electrochemical energy storage

We report a nanocomposite material exhibiting ultra-small Fe3O4 nanoparticles uniformly decorated on hollow carbon spheres (Fe3O4@HCS). The unique hierarchically-structured material displays excellent electrochemical cycling performance that exceeds the theoretical bulk capacity of Fe3O4 when used as an anode in lithium -ion batteries. In particular, it features increasing reversible capacity upon cycling yielding 1050 mAh g-1at 0.1 A g-1 in cycle 250. Comprehensive scanning and transmission electron microscopy images combined with detailed electrochemical analysis demonstrate that the outstanding electrochemical performance can be traced back to the formation and decomposition of a capacitative surface layer during dis/charging.

Automated summary

We have reported a nanocomposite material, Fe3O4@HCS, consisting of ultra-small Fe3O4 nanoparticles uniformly decorated on hollow carbon spheres. This hierarchically-structured material exhibits excellent electrochemical cycling performance as an anode in lithium-ion batteries, exceeding the theoretical capacity of Fe3O4. The reversible capacity increases to 1050 mAh g-1 at 0.1 A g-1 after 250 cycles. Scanning and transmission electron microscopy images, along with detailed electrochemical analysis, reveal that the outstanding performance is attributed to the formation and decomposition of a capacitative surface layer during discharging and charging.