Rational Construction of 2D Fe3O4@Carbon Core-Shell nanosheets as Advanced Anode Materials for High Performance Lithium Ion Half/Full Cells.

Transition metal oxides vastly limit practical applications due to their rapid capacity decay as an electrode material for lithium-ion batteries (LIBs). Here, we have successfully employed a versatile strategy to mitigate the volume expansion and low conductivity of Fe 3 O 4 via coating a thin carbon layer on the surface of Fe 3 O 4 nanosheets (NSs). Benefiting from the 2D core-shell structures, the Fe 3 O 4 @C NSs exhibit significantly improved rate performance and cycle capability compared to bare Fe 3 O 4 NSs. Along with 200 cycles, the discharge capacity at 0.5 A g -1 is shown to be 963 mAh g -1 (93% retained). Moreover, the lithium storage reaction mechanism is detailed studied by ex situ XRD and HRTEM techniques. When coupled with the commercial LiFePO 4 cathode, the full-cell retains a capacity of 133 mAh g -1 after 100 cycles at 0.1 A g -1 , demonstrating its superior energy storage performance. This work provides a guidance to construct novel 2D metal oxide-carbon composites with high performance and low cost for the field of energy storage.