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 3 O 4 by coating a thin carbon layer on the surface of Fe 3 O 4 nanosheets (NSs) was employed. Owing to the 2D core–shell structure, the Fe 3 O 4 @C NSs exhibit significantly improved rate performance and cycle capability compared with bare Fe 3 O 4 NSs. After 200 cycles, the discharge capacity at 0.5 A g −1 was 963 mA h g −1 (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 4 cathode, the resulting full cell retains a capacity of 133 mA h g −1 after 100 cycles at 0.1 A g −1 , 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.