Encapsulation of Fe2O3/NiO and Fe2O3/Co3O4 nanosheets into conductive polypyrrole for superior lithium ion storage

Fe2O3 as anode material for lithium ion batteries has been widely studied. However, structural pulverization and capacity fading induced by large volume change and low conductivity still limit its practical applications. In this work, Fe2O3/NiO/PPy and Fe2O3/Co3O4/PPy nanosheets were firstly constructed and investigated as anode materials for lithium ion batteries. The unique structures and the synergistic effect of the two components can effectively accommodate the strain of volume change, inhibit the pulverization and aggregation of the electrodes as well as enhance the electrical conductivity. Furthermore, the void spaces and interstitial sites in the Fe2O3/NiO/PPy and Fe2O3/Co3O4/PPy hybrids provide more lithium storage spaces and buffer spaces for the volumetric change during cycling. Benefiting from these advantages, the obtained Fe2O3/NiO/PPy and Fe2O3/Co3O4/PPy hybrids exhibit high reversible capacity, good cyclic performance and excellent rate capability. At the current density of 0.2 A g(-1), the Fe2O3/NiO/ PPy and Fe2O3/Co3O4/PPy display the discharge capacities of 1034 mAh g(-1) and 922 mAh g(-1) after 100 cycles, respectively. Even at high current density of 10 A g(-1), the reversible capacities still maintain at 445 mAh g(-1) for Fe2O3/NiO/PPy and 414 mAh g(-1) for Fe2O3/Co3O4/PPy after long-term cycles (1000 cycles). (C) 2018 Elsevier Ltd. All rights reserved.