Rational Construction of 2D Fe 3 O 4 @Carbon Core-Shell Nanosheets as Advanced Anode Materials for High-Performance Lithium-Ion Half/Full Cells

Transition metal oxides have vastly limited practical application as electrode materials for lithium-ion batteries (LIBs) due to their rapid capacity decay. Here, a versatile strategy to mitigate the volume expansion and low conductivity of Fe O by coating a thin carbon layer on the surface of Fe O nanosheets (NSs) was employed. Owing to the 2D core-shell structure, the Fe O @C NSs exhibit significantly improved rate performance and cycle capability compared with bare Fe O NSs. After 200 cycles, the discharge capacity at 0.5 A g was 963 mA h g (93 % retained). Moreover, the reaction mechanism of lithium storage was studied in detail by ex situ XRD and HRTEM. When coupled with a commercial LiFePO cathode, the resulting full cell retains a capacity of 133 mA h g after 100 cycles at 0.1 A g , which demonstrates its superior energy storage performance. This work provides guidance for constructing 2D metal oxide/carbon composites with high performance and low cost for the field of energy storage.