Multi-heteroatom-doped dual carbon-confined FeO nanospheres as high-capacity and long-life anode materials for lithium/sodium ion batteries.

The lithium/sodium-ion storage properties of transition metal oxides often undergo startling volume variation and poor electrical conductivity. Herein, N, P and S doped dual carbon-confined FeO nanospheres (FeO@C@G) are prepared by the multi-heteroatom-doped dual carbon-confined strategy. The first carbon layer results from multi-heteroatom-containing polymer derived N, P and S doped carbon to form FeO@doped carbon core-shell nanostructure. And the second carbon layer results from the further encapsulated reduced graphene oxide (rGO) to form FeO@doped carbon@graphene 3D architecture (FeO@C@G). As expected, the resulting FeO@C@G can be served as the universal anode materials towards lithium/sodium-ion batteries (LIBs/SIBs). Interestingly, FeO@C@G delivers higher reversible capacity of 919 mAh g at 0.1 A g for LIBs. As for SIBs, FeO@C@G also shows a high reversible capacity of 180 mAh g after 600 cycles at 0.1 A g. Furthermore, the electrochemical reaction kinetics in LIBs/SIBs are investigated and Li full cells are also assembled to demonstrate its practical application.