Nano-cubic α-Fe2O3 anode for Li+/Na+ based dual-ion full battery

Abstract

Generally, the anode materials of dual-ion batteries (DIBs) are based on the intercalation/deintercalation mechanism, display low discharge capacity and unsatisfactory cyclic stability. This work provides an ingenious nanostructure engineering strategy to prepare a type of nano-cubic α-Fe2O3 anode. Owing to the conversion mechanism, the α-Fe2O3 exhibits high specific discharge capacity and excellent stability. As the anode of a lithium based dual-ion full battery (Li-DIB), the Li-DIB displays a specific discharge capacity of 315 mAh g−1 at 0.5C. Even at a high rate of 5C, 192 mAh g−1 of the initial discharge capacity is achieved with the high initial Coulombic efficiency (ICE) of 84%. Notably, the Na-DIB on the basis of the α-Fe2O3 anode exhibits more outstanding electrochemical performances. The Na-DIB displays the highest capacity of 362 mAh g−1 with a superior capacity retention rate of 100% after 140 cycles at 2C, and 197 mAh g−1 of the initial capacity is achieved at 5C without capacity decay after 520 cycles. Moreover, the Li/Na-DIB shows an extremely low self-discharge rate and stable fast charging-slow discharging performance. Therefore, this work puts forward excellent Li-DIB and Na-DIB systems, endowing α-Fe2O3 a promising candidate for electrochemical energy storage, and the method proposed herein can provide a novel idea for the manufacture of other hollow structures or geometric shapes.